Sequence and mechanical implications of titin's PEVK region.

A widely used titin monoclonal antibody (9D10) was epitope mapped to the PEVK region in the I-band portion of titin. Sequence analysis of the titin PEVK region revealed a large number of 28 amino acid modules (termed "PPAK" repeats) alternating with glutamic acid rich segments. Species differences in cardiac rest tension could not be ascribed to differences in the PEVK length of the N2B titin isoform. The low rest tension generated by dog cardiac muscle also does not appear to be explained by the N2 and PEVK segment lengths in the N2A titin isoform.