Heterodimerization of Endothelin-converting Enzyme-1 Isoforms Regulates the Subcellular Distribution of This Metalloprotease

Abstract

Endothelin-converting enzyme (ECE) is a membrane metalloprotease that generates endothelin from its direct precursor big endothelin. Four isoforms of ECE-1 are produced from a single gene through the use of alternate promoters. These isoforms share the same extracellular catalytic domain and contain unique cytosolic tails, which results in their specific subcellular targeting. We investigated the distribution of ECE-1 isoforms in transfected AtT-20 neuroendocrine cells. Whereas ECE-1a and 1c were present at the plasma membrane, ECE-1b and ECE-1d were retained inside the cells. We found that both intracellular isoforms were concentrated in the endosomal system: ECE-1d in recycling endosomes, and ECE-1b in late endosomes/multivesicular bodies. Leucine-based motifs were involved in the intracellular retention of these isoforms, and the targeting of ECE-1b to the degradation pathway required an additional signal in the N terminus. The concentration of ECE-1 isoforms in the endosomal system suggested new functions for these enzymes. Potential novel functions include redistribution of other isoforms through direct interaction. We have showed that ECE-1 isoforms could heterodimerize, and that in such heterodimers the ECE-1b targeting signal was dominant. Interaction of a plasma membrane isoform with ECE-1b resulted in its intracellular localization and decreased its extracellular activity. These data demonstrated that the targeting signals specific for ECE-1b constitute a regulatory domain per se that could modulate the localization and the activity of other isoforms. Endothelin-converting enzyme (ECE) is a membrane metalloprotease that generates endothelin from its direct precursor big endothelin. Four isoforms of ECE-1 are produced from a single gene through the use of alternate promoters. These isoforms share the same extracellular catalytic domain and contain unique cytosolic tails, which results in their specific subcellular targeting. We investigated the distribution of ECE-1 isoforms in transfected AtT-20 neuroendocrine cells. Whereas ECE-1a and 1c were present at the plasma membrane, ECE-1b and ECE-1d were retained inside the cells. We found that both intracellular isoforms were concentrated in the endosomal system: ECE-1d in recycling endosomes, and ECE-1b in late endosomes/multivesicular bodies. Leucine-based motifs were involved in the intracellular retention of these isoforms, and the targeting of ECE-1b to the degradation pathway required an additional signal in the N terminus. The concentration of ECE-1 isoforms in the endosomal system suggested new functions for these enzymes. Potential novel functions include redistribution of other isoforms through direct interaction. We have showed that ECE-1 isoforms could heterodimerize, and that in such heterodimers the ECE-1b targeting signal was dominant. Interaction of a plasma membrane isoform with ECE-1b resulted in its intracellular localization and decreased its extracellular activity. These data demonstrated that the targeting signals specific for ECE-1b constitute a regulatory domain per se that could modulate the localization and the activity of other isoforms. endothelin adrenocorticotropic hormone big endothelin endothelin-converting enzyme neutral endopeptidase trans-Golgi network phosphate-buffered saline Dulbecco's modified Eagle's medium 1,4-piperazinediethanesulfonic acid Endothelins (ET1-1, ET-2, and ET-3) are 21-residue peptides derived from three distinct genes (1Inoue A. Yanagisawa M. Kimura S. Kasuya Y. Miyauchi T. Goto K. Masaki T. Proc. Natl. Acad. Sci. U. S. A. 1989; 86: 2863-2867Crossref PubMed Scopus (2556) are that an in the of the and and T. PubMed Scopus Endothelins are demonstrated the of the genes for the of and and of the genes for their and Y. T. K. T. PubMed Scopus K. A. Yanagisawa M. PubMed Scopus K. A. Yanagisawa M. PubMed Scopus K. Yanagisawa T. M. Yanagisawa M. PubMed the of endothelin is with and with PubMed Scopus PubMed Scopus PubMed Scopus to such a of through and Endothelins are in the that a are at a in to an big endothelin A. T. T. Masaki T. PubMed Scopus M. K. PubMed Scopus which is of activity K. Y. K. T. M. PubMed Scopus is endothelin enzyme (ECE) at a which the in the extracellular medium and in the that with A. S. Yanagisawa M. PubMed Scopus K. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus PubMed Scopus the the enzyme and the of endothelin. the other M. Yanagisawa M. PubMed Scopus and S. A. M. PubMed Scopus the enzyme and the and three the the enzyme and the in A. M. Yanagisawa M. A. PubMed Scopus the of endothelin through extracellular of The distribution of a in the pathway of is a membrane of the neutral endopeptidase with an cytosolic and a catalytic other of is M. T. T. PubMed Scopus M. K. K. K. M. Y. K. PubMed Scopus K. M. K. PubMed Scopus genes for ECE-1 and have M. T. T. PubMed Scopus K. M. K. PubMed A. S. Yanagisawa M. PubMed Scopus Yanagisawa M. PubMed Scopus ECE-1 a distribution and is at The of the ECE-1 gene resulted in a that both the of the of and of the of ECE-1 in the endothelin system Yanagisawa M. PubMed the other the of the gene in of the was with the ECE-1 gene S. Yanagisawa M. PubMed Scopus ECE-1 is in the of in of and neuroendocrine A. S. Yanagisawa M. PubMed Scopus M. K. K. K. M. Y. K. PubMed Scopus S. A. M. PubMed Scopus and PubMed Scopus for K. PubMed Scopus Four isoforms of ECE-1 have PubMed Scopus and A. A. PubMed Scopus for K. A. Sci. PubMed Scopus and a gene for Y. PubMed Scopus S. M. M. PubMed Scopus ECE-1 isoforms from the use of alternate of specific PubMed Scopus A. A. PubMed Scopus M. S. M. PubMed Scopus the ECE-1 isoforms share the same catalytic domain and in their N which for their cytosolic these are for their the of isoforms in their subcellular the of the intracellular and extracellular of the subcellular distribution of isoforms a in the of the endothelin system and an for the of in to the intracellular localization of ECE-1 in M. K. K. K. M. Y. K. PubMed Scopus K. K. M. K. Sci. PubMed Scopus of these were to isoform to the of that and was the of ECE-1 isoforms in transfected cells. these ECE-1a and were to the plasma membrane, ECE-1b was to intracellular and ECE-1d an distribution A. A. PubMed Scopus A. U. PubMed Scopus A. PubMed Scopus A. A. Sci. PubMed constitute ECE-1 in K. PubMed Scopus PubMed Scopus these and are the and the We the neuroendocrine AtT-20 a These are that are in the and of adrenocorticotropic hormone these investigated the subcellular distribution and the of ECE-1 isoforms, the of intracellular ECE-1 is a of and the of is to the of these ECE-1 unique is present and both at the and in intracellular the present have investigated these of ECE-1 the of the intracellular distribution of the ECE-1 isoforms in the pathway and in the endosomal The isoforms in intracellular ECE-1b and distinct of distribution in the endosomal system: ECE-1d was present in the recycling and ECE-1b in the late endosomes/multivesicular bodies. could that ECE-1 isoforms The of such heterodimers suggested a novel for the targeting of We showed that the targeting signal for the intracellular distribution of ECE-1b could the plasma membrane ECE-1a to the endosomal These data demonstrated that the specific N of ECE-1b a regulatory domain that is to the distribution of other ECE-1 isoforms. a regulatory could ECE-1 isoforms A. U. PubMed Scopus A. A. PubMed Scopus was in the AtT-20 to the of in the activity of neuroendocrine through and A. PubMed Scopus for T. PubMed Scopus Endothelins have in the of neuroendocrine T. S. PubMed Scopus the that ECE-1 was to the neuroendocrine results the that was in of the intracellular isoforms were in the data suggested that the endothelin in the from in the of in is the that is required for ECE-1 to endothelin from its precursor T. T. Kimura Masaki T. PubMed Scopus that ECE-1 was concentrated in the is PubMed Scopus ECE-1 is through The intracellular of in the a for ECE-1 have that a plasma membrane could endothelin in the pathway in the extracellular medium PubMed Scopus Whereas ECE-1b and ECE-1d could endothelin in the these isoforms specific ECE-1a 1c for of is the from that and an intracellular isoform of the of intracellular of ECE-1 A. S. Yanagisawa M. PubMed Scopus the other could the required for of in the of the and the Yanagisawa M. PubMed Scopus and of the isoforms of were found in intracellular S. M. M. PubMed Scopus at the intracellular ECE-1b have produced ECE-1b was in the was with the in K. K. M. K. Sci. and with in transfected A. U. PubMed Scopus A. A. Sci. PubMed the of ECE-1b in late endosomes/multivesicular in transfected and A. PubMed Scopus A. A. Sci. PubMed results were in with these demonstrated that ECE-1d was present in the endosomal concentrated in the recycling We showed that ECE-1b and were the plasma membrane and three of extracellular activity was from ECE-1b and these isoforms were to the of a of which of retained these ECE-1 isoforms at the plasma membrane, and with these ECE-1b was with a for endosomes, which is the intracellular A. PubMed Scopus was for the intracellular retention of isoform PubMed Scopus A. A. Sci. PubMed the present demonstrated that the intracellular localization of ECE-1d the of a specific We that a to 1c and was involved in ECE-1b intracellular retention A. A. Sci. PubMed found that signal is involved in ECE-1b the other the ECE-1b specific was for the degradation of was motifs have at of intracellular in the the and the plasma membrane PubMed Scopus the for the of the involved to S. S. PubMed Scopus of suggested that the of ECE-1b additional signal to the the of the ECE-1b the plasma membrane with the of ECE-1d the and motifs modified ECE-1d degradation and that of the the of ECE-1b of the of ECE-1d resulted in the degradation of results suggested that ECE-1b N signal that in the The additional signal could to a to a that the of the for an for to the degradation the of isoforms of Y. T. Yanagisawa M. M. PubMed Scopus have for the targeting of ECE-1b to the plasma membrane, and for the of ECE-1a to Y. T. Yanagisawa M. M. PubMed Scopus that ECE-1b to which found to the plasma membrane, and that ECE-1a is with the targeting signals for ECE-1a are present in of ECE-1 isoforms in the endosomal system could to novel of is present in these ECE-1 could constitute an intracellular that could to the plasma membrane of the suggested the of ECE-1b and ECE-1d and plasma the intracellular retention of isoform could the distribution of other isoforms through direct interaction. ECE-1 is the of ECE-1 found M. T. T. PubMed Scopus M. K. K. K. M. Y. K. PubMed Scopus K. M. K. PubMed Scopus We have showed that ECE-1 is present the plasma membrane of A. PubMed The present of ECE-1 demonstrated that the of ECE-1 is a to the isoforms. in the could the of that to The present in the catalytic is for the K. M. K. PubMed Scopus The of ECE-1 investigated of a the and the subcellular distribution of modified the of ECE-1 K. M. K. PubMed Scopus S. K. K. PubMed Scopus for the of heterodimers in isoforms. The of the of heterodimers in these was to the of of and to the of specific for ECE-1b 1c AtT-20 that the isoform with the plasma membrane and which the intracellular transfected could the of isoforms were in intracellular and the extracellular activity of ECE-1a was demonstrated that ECE-1a was to the late endosomes/multivesicular that of these isoforms the of ECE-1b at the plasma membrane, the of ECE-1b was in with the of ECE-1b to through a ECE-1a and the plasma membrane the of a signal these data suggested that could ECE-1 extracellular activity through the of the plasma membrane isoform to intracellular a could at at the could the of suggested that ECE-1 in the The of ECE-1 isoforms is the of alternate in the gene PubMed Scopus A. A. PubMed Scopus M. S. M. PubMed Scopus have for the of PubMed Scopus M. U. A. PubMed Scopus A. S. A. T. M. PubMed Scopus S. PubMed Scopus could modulate the from plasma membrane activity to intracellular activity at the of of the ECE-1 activity was the of ECE-1 isoforms was PubMed Scopus of could to the of the isoforms. have for the of at the plasma membrane M. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus K. PubMed Scopus S. M. PubMed Scopus PubMed Scopus the of ECE-1b and ECE-1d the plasma membrane and could a for the plasma membrane ECE-1a and through a plasma membrane are through of of activity ECE-1 is a and the present that of ECE-1 isoforms could constitute a for their distribution their extracellular activity. could for other and which are to Endothelins (ET1-1, ET-2, and ET-3) are 21-residue peptides derived from three distinct genes (1Inoue A. Yanagisawa M. Kimura S. Kasuya Y. Miyauchi T. Goto K. Masaki T. Proc. Natl. Acad. Sci. U. S. A. 1989; 86: 2863-2867Crossref PubMed Scopus (2556) are that an in the of the and and T. PubMed Scopus Endothelins are demonstrated the of the genes for the of and and of the genes for their and Y. T. K. T. PubMed Scopus K. A. Yanagisawa M. PubMed Scopus K. A. Yanagisawa M. PubMed Scopus K. Yanagisawa T. M. Yanagisawa M. PubMed the of endothelin is with and with PubMed Scopus PubMed Scopus PubMed Scopus to such a of through and Endothelins are in the that a are at a in to an big endothelin A. T. T. Masaki T. PubMed Scopus M. K. PubMed Scopus which is of activity K. Y. K. T. M. PubMed Scopus is endothelin enzyme (ECE) at a which the in the extracellular medium and in the that with A. S. Yanagisawa M. PubMed Scopus K. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus PubMed Scopus the the enzyme and the of endothelin. the other M. Yanagisawa M. PubMed Scopus and S. A. M. PubMed Scopus the enzyme and the and three the the enzyme and the in A. M. Yanagisawa M. A. PubMed Scopus the of endothelin through extracellular of The distribution of a in the pathway of is a membrane of the neutral endopeptidase with an cytosolic and a catalytic other of is M. T. T. PubMed Scopus M. K. K. K. M. Y. K. PubMed Scopus K. M. K. PubMed Scopus genes for ECE-1 and have M. T. T. PubMed Scopus K. M. K. PubMed A. S. Yanagisawa M. PubMed Scopus Yanagisawa M. PubMed Scopus ECE-1 a distribution and is at The of the ECE-1 gene resulted in a that both the of the of and of the of ECE-1 in the endothelin system Yanagisawa M. PubMed the other the of the gene in of the was with the ECE-1 gene S. Yanagisawa M. PubMed Scopus ECE-1 is in the of in of and neuroendocrine A. S. Yanagisawa M. PubMed Scopus M. K. K. K. M. Y. K. PubMed Scopus S. A. M. PubMed Scopus and PubMed Scopus for K. PubMed Scopus Four isoforms of ECE-1 have PubMed Scopus and A. A. PubMed Scopus for K. A. Sci. PubMed Scopus and a gene for Y. PubMed Scopus S. M. M. PubMed Scopus ECE-1 isoforms from the use of alternate of specific PubMed Scopus A. A. PubMed Scopus M. S. M. PubMed Scopus the ECE-1 isoforms share the same catalytic domain and in their N which for their cytosolic these are for their the of isoforms in their subcellular the of the intracellular and extracellular of the subcellular distribution of isoforms a in the of the endothelin system and an for the of in to the intracellular localization of ECE-1 in M. K. K. K. M. Y. K. PubMed Scopus K. K. M. K. Sci. PubMed Scopus of these were to isoform to the of that and was the of ECE-1 isoforms in transfected cells. these ECE-1a and were to the plasma membrane, ECE-1b was to intracellular and ECE-1d an distribution A. A. PubMed Scopus A. U. PubMed Scopus A. PubMed Scopus A. A. Sci. PubMed constitute ECE-1 in K. PubMed Scopus PubMed Scopus these and are the and the We the neuroendocrine AtT-20 a These are that are in the and of adrenocorticotropic hormone these investigated the subcellular distribution and the of ECE-1 isoforms, the of intracellular ECE-1 is a of and the of is to the of these ECE-1 unique is present and both at the and in intracellular the present have investigated these of ECE-1 the of the intracellular distribution of the ECE-1 isoforms in the pathway and in the endosomal The isoforms in intracellular ECE-1b and distinct of distribution in the endosomal system: ECE-1d was present in the recycling and ECE-1b in the late endosomes/multivesicular bodies. could that ECE-1 isoforms The of such heterodimers suggested a novel for the targeting of We showed that the targeting signal for the intracellular distribution of ECE-1b could the plasma membrane ECE-1a to the endosomal These data demonstrated that the specific N of ECE-1b a regulatory domain that is to the distribution of other ECE-1 isoforms. a regulatory could ECE-1 isoforms A. U. PubMed Scopus A. A. PubMed Scopus was in the AtT-20 to the of in the activity of neuroendocrine through and A. PubMed Scopus for T. PubMed Scopus Endothelins have in the of neuroendocrine T. S. PubMed Scopus the that ECE-1 was to the neuroendocrine results the that was in of the intracellular isoforms were in the data suggested that the endothelin in the from in the of in is the that is required for ECE-1 to endothelin from its precursor T. T. Kimura Masaki T. PubMed Scopus that ECE-1 was concentrated in the is PubMed Scopus ECE-1 is through The intracellular of in the a for ECE-1 have that a plasma membrane could endothelin in the pathway in the extracellular medium PubMed Scopus Whereas ECE-1b and ECE-1d could endothelin in the these isoforms specific ECE-1a 1c for of is the from that and an intracellular isoform of the of intracellular of ECE-1 A. S. Yanagisawa M. PubMed Scopus the other could the required for of in the of the and the Yanagisawa M. PubMed Scopus and of the isoforms of were found in intracellular S. M. M. PubMed Scopus at the intracellular ECE-1b have produced ECE-1b was in the was with the in K. K. M. K. Sci. and with in transfected A. U. PubMed Scopus A. A. Sci. PubMed the of ECE-1b in late endosomes/multivesicular in transfected and A. PubMed Scopus A. A. Sci. PubMed results were in with these demonstrated that ECE-1d was present in the endosomal concentrated in the recycling We showed that ECE-1b and were the plasma membrane and three of extracellular activity was from ECE-1b and these isoforms were to the of a of which of retained these ECE-1 isoforms at the plasma membrane, and with these ECE-1b was with a for endosomes, which is the intracellular A. PubMed Scopus was for the intracellular retention of isoform PubMed Scopus A. A. Sci. PubMed the present demonstrated that the intracellular localization of ECE-1d the of a specific We that a to 1c and was involved in ECE-1b intracellular retention A. A. Sci. PubMed found that signal is involved in ECE-1b the other the ECE-1b specific was for the degradation of was motifs have at of intracellular in the the and the plasma membrane PubMed Scopus the for the of the involved to S. S. PubMed Scopus of suggested that the of ECE-1b additional signal to the the of the ECE-1b the plasma membrane with the of ECE-1d the and motifs modified ECE-1d degradation and that of the the of ECE-1b of the of ECE-1d resulted in the degradation of results suggested that ECE-1b N signal that in the The additional signal could to a to a that the of the for an for to the degradation the of isoforms of Y. T. Yanagisawa M. M. PubMed Scopus have for the targeting of ECE-1b to the plasma membrane, and for the of ECE-1a to Y. T. Yanagisawa M. M. PubMed Scopus that ECE-1b to which found to the plasma membrane, and that ECE-1a is with the targeting signals for ECE-1a are present in of ECE-1 isoforms in the endosomal system could to novel of is present in these ECE-1 could constitute an intracellular that could to the plasma membrane of the suggested the of ECE-1b and ECE-1d and plasma the intracellular retention of isoform could the distribution of other isoforms through direct interaction. ECE-1 is the of ECE-1 found M. T. T. PubMed Scopus M. K. K. K. M. Y. K. PubMed Scopus K. M. K. PubMed Scopus We have showed that ECE-1 is present the plasma membrane of A. PubMed The present of ECE-1 demonstrated that the of ECE-1 is a to the isoforms. in the could the of that to The present in the catalytic is for the K. M. K. PubMed Scopus The of ECE-1 investigated of a the and the subcellular distribution of modified the of ECE-1 K. M. K. PubMed Scopus S. K. K. PubMed Scopus for the of heterodimers in isoforms. The of the of heterodimers in these was to the of of and to the of specific for ECE-1b 1c AtT-20 that the isoform with the plasma membrane and which the intracellular transfected could the of isoforms were in intracellular and the extracellular activity of ECE-1a was demonstrated that ECE-1a was to the late endosomes/multivesicular that of these isoforms the of ECE-1b at the plasma membrane, the of ECE-1b was in with the of ECE-1b to through a ECE-1a and the plasma membrane the of a signal these data suggested that could ECE-1 extracellular activity through the of the plasma membrane isoform to intracellular a could at at the could the of suggested that ECE-1 in the The of ECE-1 isoforms is the of alternate in the gene PubMed Scopus A. A. PubMed Scopus M. S. M. PubMed Scopus have for the of PubMed Scopus M. U. A. PubMed Scopus A. S. A. T. M. PubMed Scopus S. PubMed Scopus could modulate the from plasma membrane activity to intracellular activity at the of of the ECE-1 activity was the of ECE-1 isoforms was PubMed Scopus of could to the of the isoforms. have for the of at the plasma membrane M. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus K. PubMed Scopus S. M. PubMed Scopus PubMed Scopus the of ECE-1b and ECE-1d the plasma membrane and could a for the plasma membrane ECE-1a and through a plasma membrane are through of of activity ECE-1 is a and the present that of ECE-1 isoforms could constitute a for their distribution their extracellular activity. could for other and which are to ECE-1 to the of these ECE-1 unique is present and both at the and in intracellular the present have investigated these of ECE-1 the of the intracellular distribution of the ECE-1 isoforms in the pathway and in the endosomal The isoforms in intracellular ECE-1b and distinct of distribution in the endosomal system: ECE-1d was present in the recycling and ECE-1b in the late endosomes/multivesicular bodies. could that ECE-1 isoforms The of such heterodimers suggested a novel for the targeting of We showed that the targeting signal for the intracellular distribution of ECE-1b could the plasma membrane ECE-1a to the endosomal These data demonstrated that the specific N of ECE-1b a regulatory domain that is to the distribution of other ECE-1 isoforms. a regulatory could ECE-1 isoforms A. U. PubMed Scopus A. A. PubMed Scopus was in the AtT-20 to the of in the activity of neuroendocrine through and A. PubMed Scopus for T. PubMed Scopus Endothelins have in the of neuroendocrine T. S. PubMed Scopus the that ECE-1 was to the neuroendocrine results the that was in of the intracellular isoforms were in the data suggested that the endothelin in the from in the of in is the that is required for ECE-1 to endothelin from its precursor T. T. Kimura Masaki T. PubMed Scopus that ECE-1 was concentrated in the is PubMed Scopus ECE-1 is through The intracellular of in the a for ECE-1 have that a plasma membrane could endothelin in the pathway in the extracellular medium PubMed Scopus Whereas ECE-1b and ECE-1d could endothelin in the these isoforms specific ECE-1a 1c for of is the from that and an intracellular isoform of the of intracellular of ECE-1 A. S. Yanagisawa M. PubMed Scopus the other could the required for of in the of the and the Yanagisawa M. PubMed Scopus and of the isoforms of were found in intracellular S. M. M. PubMed Scopus at the intracellular ECE-1b have produced ECE-1b was in the was with the in K. K. M. K. Sci. and with in transfected A. U. PubMed Scopus A. A. Sci. PubMed the of ECE-1b in late endosomes/multivesicular in transfected and A. PubMed Scopus A. A. Sci. PubMed results were in with these demonstrated that ECE-1d was present in the endosomal concentrated in the recycling We showed that ECE-1b and were the plasma membrane and three of extracellular activity was from ECE-1b and these isoforms were to the of a of which of retained these ECE-1 isoforms at the plasma membrane, and with these ECE-1b was with a for endosomes, which is the intracellular A. PubMed Scopus The was for the intracellular retention of isoform PubMed Scopus A. A. Sci. PubMed the present demonstrated that the intracellular localization of ECE-1d the of a specific We that a to 1c and was involved in ECE-1b intracellular retention A. A. Sci. PubMed found that signal is involved in ECE-1b the other the ECE-1b specific was for the degradation of was motifs have at of intracellular in the the and the plasma membrane PubMed Scopus the for the of the involved to S. S. PubMed Scopus of suggested that the of ECE-1b additional signal to the the of the ECE-1b the plasma membrane with the of ECE-1d the and motifs modified ECE-1d degradation and that of the the of ECE-1b of the of ECE-1d resulted in the degradation of results suggested that ECE-1b N signal that in the The additional signal could to a to a that the of the for an for to the degradation the of isoforms of Y. T. Yanagisawa M. M. PubMed Scopus have for the targeting of ECE-1b to the plasma membrane, and for the of ECE-1a to Y. T. Yanagisawa M. M. PubMed Scopus that ECE-1b to which found to the plasma membrane, and that ECE-1a is with the targeting signals for ECE-1a are present in The of ECE-1 isoforms in the endosomal system could to novel of is present in these ECE-1 could constitute an intracellular that could to the plasma membrane of the suggested the of ECE-1b and ECE-1d and plasma the intracellular retention of isoform could the distribution of other isoforms through direct interaction. ECE-1 is the of ECE-1 found M. T. T. PubMed Scopus M. K. K. K. M. Y. K. PubMed Scopus K. M. K. PubMed Scopus We have showed that ECE-1 is present the plasma membrane of A. PubMed The present of ECE-1 demonstrated that the of ECE-1 is a to the isoforms. in the could the of that to The present in the catalytic is for the K. M. K. PubMed Scopus The of ECE-1 investigated of a the and the subcellular distribution of modified the of ECE-1 K. M. K. PubMed Scopus S. K. K. PubMed Scopus for the of heterodimers in isoforms. The of the of heterodimers in these was to the of of and to the of specific for ECE-1b 1c AtT-20 that the isoform with the plasma membrane and which the intracellular transfected could the of isoforms were in intracellular and the extracellular activity of ECE-1a was demonstrated that ECE-1a was to the late endosomes/multivesicular that of these isoforms the of ECE-1b at the plasma membrane, the of ECE-1b was in with the of ECE-1b to through a ECE-1a and the plasma membrane the of a signal these data suggested that could ECE-1 extracellular activity through the of the plasma membrane isoform to intracellular a could at at the could the of suggested that ECE-1 in the The of ECE-1 isoforms is the of alternate in the gene PubMed Scopus A. A. PubMed Scopus M. S. M. PubMed Scopus have for the of PubMed Scopus M. U. A. PubMed Scopus A. S. A. T. M. PubMed Scopus S. PubMed Scopus could modulate the from plasma membrane activity to intracellular activity at the of of the ECE-1 activity was the of ECE-1 isoforms was PubMed Scopus of could to the of the isoforms. have for the of at the plasma membrane M. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus K. PubMed Scopus S. M. PubMed Scopus PubMed Scopus the of ECE-1b and ECE-1d the plasma membrane and could a for the plasma membrane ECE-1a and through a plasma membrane are through of of activity ECE-1 is a and the present that of ECE-1 isoforms could constitute a for their distribution their extracellular activity. could for other and which are to We M. and for was with the of We K. for the We are to S. of at M. and of for the of and