Loss of hyaluronate-dependent coat during myoblast fusion.

Cultured myoblasts were found to exhibit extensive, Streptomyces hyaluronidase-sensitive pericellular coats as revealed by exclusion of particles (fixed red blood cells). These coats are not discernible subsequent to fusion of the myoblasts to form myotubes. The myoblasts contained 2.5 times more hyaluronate attached to their cell surface than myotubes when the data was expressed per unit of protein, but no change in hyaluronate was evident on a per DNA basis. Hyaluronidase activities in the cultures were equivalent when expressed per unit of protein. We conclude that, although the myotubes accumulate larger amounts of protein than myoblasts, there is no compensatory increase in hyaluronate.