AJP - Cell Physiology, Vol 267, Issue 2 C443-C449, Copyright © 1994 by American Physiological Society
Coordinate changes in C protein and myosin expression during skeletal muscle hypertrophy
K. M. McCormick, K. M. Baldwin and F. Schachat
Department of Cell Biology, Duke University Medical School, Durham, North Carolina 27710.
In this study, two new C protein isoforms in adult rat skeletal muscle were
resolved using sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
These isoforms migrated between previously identified fast (Cf) and slow
(Cs) C protein isoforms; hence they were named intermediate C proteins (Ci1
and Ci2). Cyanogen bromide peptide mapping and Western blotting showed that
the intermediate isoforms were more similar to Cs than Cf. The distribution
of specific C protein and myosin heavy chain (MHC) isoforms was highly
correlated in several hindlimb muscles, suggesting that the expression of
these two thick-filament proteins is coordinated. This notion was tested by
determining whether specific C protein and MHC isoforms change in parallel
during muscle hypertrophy. Eight weeks after ablation of its synergists,
the overloaded plantaris muscle showed significant increases in type IIa
MHC and intermediate C protein, with corresponding decreases in type IIb
MHC and Cf protein. These results indicate that C protein expression is
linked to MHC expression during plantaris muscle hypertrophy.
