Identification and quantification of actin isoforms in vertebrate cells and tissues

Abstract

The cytoskeletal protein actin exists in vertebrates as six different isoforms, which are difficult to identify conclusively because of a high degree (greater than 90%) of overall sequence homology. We have used IEF immunoblotting in combination with a panel of isoform-specific and -selective antibodies to analyze the actin isoform composition of nine tissues from adult rat. In three nonmuscle tissues (lung, spleen, and testis), we detected a previously unreported isoform that we identified as smooth muscle alpha. The IEF immunoblot technique was also used to quantify the proportions of the isoforms expressed in these nine rat tissues.