The Yeast Vps10p Cytoplasmic Tail Mediates Lysosomal Sorting in Mammalian Cells and Interacts with Human GGAs

Abstract

Yeast Vps10p is a receptor for transport of the soluble vacuolar hydrolase carboxypeptidase Y to the lysosome-like vacuole. Its functional equivalents in mammalian cells are the mannose 6-phosphate receptors that mediate sorting to lysosomes of mannose 6-phosphate-containing lysosomal proteins. A chimeric receptor was constructed by substituting the cytoplasmic domain of M(r) 300,000 mannose 6-phosphate receptor with the Vps10p cytoplasmic tail. Expression of the chimera in cells lacking endogenous mannose 6-phosphate receptors resulted in a subcellular receptor distribution and an efficiency in sorting of lysosomal enzymes similar to that of the wild type M(r) 300,000 mannose 6-phosphate receptor. Moreover, the cytoplasmic tail of the Vps10p was found to interact with GGA1 and GGA2, two mammalian members of a recently discovered family of clathrin-binding cytosolic proteins that participate in trans-Golgi network-endosome trafficking in both mammals and yeast. Our findings suggest a conserved machinery for Golgi-endosome/vacuole sorting and may serve as a model for future studies of yeast proteins.