[Titin isoforms].

The titin isoform composition in skeletal and cardiac muscles of humans and animals has been studied using SDS elecrtophoresis in agarose-strengthened 1.3-2.3% polyacrylamide gels modified by us and immunoblot analysis in order to reveal new titin isoforms with molecular weights of more than 3700 kDa. The experimental data obtained have provided a basis for the suggestion that the titin bands of high molecular weights discovered by us are intact titin isoforms, while the titin bands designated on electrophoregrams as N2A, N2B and N2BA isoforms are their fragments.