Generation of multiple troponin T isoforms is a common feature of the muscles in various chordate animals.

1. Troponin T (TNT) expressed in various vertebrate skeletal and ascidian smooth muscles was examined by two-dimensional electrophoresis in combination with immunoblotting. 2. A monoclonal anti-TNT antibody, NT-302, exhibited binding ability to various TNT variants in the vertebrate and protochordate animals. 3. TNT isoform pattern differed among the animals, but the existence of multiple TNT isoforms in a single muscle tissue was the general feature of all the animals examined.