Int. J. Dev. Biol. 37: 305 - 310 (1993)

Vol 37, Issue 2

Synthesis and secretion of a 38-kDa glycopolypeptide coincides with L6 myoblast fusion

Published: 1 June 1993

K Metsikkö and H K Väänänen

Department of Anatomy, University of Oulu, Finland.

Abstract

Rat L6 myoblastic cell line fused rapidly after two day cultivation in a medium containing horse serum and insulin. We analyzed whether the induction of plasma membrane or secreted proteins occurred simultaneously with ongoing fusion. Thus the cells were metabolically labeled with [35S]methionine followed by biotinylation of the cell surface proteins. Detergent-solubilized proteins derivatized with biotin were isolated with streptavidin-agarose and subjected to SDS polyacrylamide gel electrophoresis. This analysis did not show fusion-associated induction of any surface proteins. However, analysis of the microsomal fraction revealed a fusion-associated 38-kDa glycopolypeptide. This polypeptide appeared simultaneously with the formation of the multinucleated cells and then declined with decreasing fusion activity. Pulse-chase labeling experiments showed that the 38-kDa component was secreted into the medium. These results indicate that a secreted protein component is induced during the fusion of L6 myoblasts.