Cytoplasmic actin in postsynaptic structures at the neuromuscular junction.

Abstract

An antibody prepared against Aplysia (mollusk) body-wall actin that specifically reacts with certain forms of cytoplasmic actin in mammalian cells was used to probe for the presence of actin at the rat neuromuscular junction. Immunocytochemical studies showed that actin or an actinlike molecule is concentrated at neuromuscular junctions of normal and denervated adult rat muscle fibers. Actin is present at the neuromuscular junctions of fibers of developing diaphragm muscles as early as embryonic day 18, well before postsynaptic folds are formed. Cytoplasmic actin may play a role in the clustering or stabilization of acetylcholine receptors at the neuromuscular junction.