These studies have examined the distribution of plasma membrane intramembranous particles (PMP) visualized by freeze fracture and concanavalin A receptors seen by ultrastructural cytochemistry of differentiated and undifferentiated L6 myoblasts. Undifferentiated mononucleated cells have a clustered distribution of PMP on the majority of the fracture faces. Associated with cell differentiation and cell fusion a more uniform distribution of PMP is observed. Changes also occur with myoblast differentiation in the topography and dynamics of receptors bound to concanavalin A. If undifferentiated or differentiated cells are fixed with glutaraldehyde and then reacted with con-A a uniform distribution of con-A is seen on the cell surfaces. In contrast to this if unfixed live cells are reacted at 37° C with con-A a profound redistribution occurs on differentiated cells (greater than 99% showing redistribution) while receptors remain in a uniform array on undifferentiated cells (approximately 95% uniform distribution). In addition to the membrane binding, con-A is observed to bind to an extracellular filamentous matrix seen in high density undifferentiated cultures which then appears to be degraded with differentiation and myoblast fusion. These studies show that a number of membrane changes, both structural and dynamic occur with myoblast differentiation.
|Original language||English (US)|
|Number of pages||7|
|State||Published - 1979|
Bibliographical noteFunding Information:
Acknowledgements: We wish to thank E. S. Benson for advice and support, S. Palm and J. Ihrke for their excellent technical assistance, and C. Furcht for assistance in preparation of this manuscript. This work was supported by grants from the NIH-NCI #1R01-CA21463-01 and the University Leukemia Task Force to L.T.F.
- phosphate buffered saline
- plasma membrane intramembranous particle