Correlation between fusion and the developmental regulation of membrane glycoproteins in L6 myoblasts.

Expression of membrane glycoproteins in L6 myoblasts during the course of myogenesis was investigated. The effects of several inhibitors of myoblast fusion and differentiation were also studied. The predominant change in plasma membrane proteins concomitant with fusion was the reduction in the expression of a major 105-kDa glycoprotein and the appearance of a 90-kDa glycoprotein. This change was blocked by bromodeoxyuridine and two metalloendoprotease inhibitors, phenanthroline and benzyloxycarbonyl-Ser-Leu-NH2, all of which have been shown to inhibit myoblast fusion. The nature of this inhibition suggests a role for an endogenous metalloendoprotease in myoblast commitment to terminal differentiation. The possible function of the developmentally regulated glycoproteins in myogenesis is also discussed.