Talin is a post-synaptic component of the rat neuromuscular junction

Talin is a protein, recently discovered in chicken gizzard, which occurs at sites of actin-plasma membrane interaction in several cell types. Vinculin also occurs at many of these sites, possibly in association with talin. In this study, three antisera against talin were used to probe the neuromuscular junction of rat skeletal muscle, which is also a site of vinculin accumulation. By immunofluorescence, all three sera stained the junction strongly in frozen sections of rat diaphragm. The extrajunctional periphery was lightly and irregularly stained in some muscle cells; others seemed not to be stained outside the junction. Staining remained at junctions and increased in extrajunctional regions of muscle denervated 6 weeks before sacrifice. The staining in all cases was abolished by competition with purified talin. One serum tested by immunoblotting recognized one protein at Mr 215 000 (identical with the value for chicken gizzard talin) and traces of a second at Mr 190 000 (corresponding to a known proteolytic fragment of talin). We conclude that rat muscle talin is similar in its general protein structure to chicken gizzard talin, and is a post-synaptic component of the neuromuscular junction.