Gamma actin, spectrin, and intermediate filament proteins colocalize with vinculin at costameres, myofibril-to-sarcolemma attachment sites

Abstract

Localization of vinculin at the sarcolemma of striated muscle fibers defines an orthogonal lattice. The costameres of the lattice are the riblike bands of vinculin that run perpendicular to the long axis of the fiber, repeat in register with I bands of the subjacent myofibrils, and seem to couple the myofibril to the sarcolemma [Pardo et al 1982, 1983a]. The colocalization studies presented in this paper show that gamma actin, spectrin, and intermediate filament antigens are additional components of this lattice of costameres. In addition, the results show that gamma actin and spectrin are also components of the internal network of collars, first visualized with antibody to desmin [Granger and Lazarides, 1978], that connects the myofibrils to each other at the level of the Z line.