Homology of the 74-kD cytoplasmic dynein subunit with a flagellar dynein polypeptide suggests an intracelhilar targeting function

Abstract. In previous work we found cytoplasmic dynein to be a complex of two catalytic heavy chains and at least seven co-purifying polypeptides of unknown function. The most prominent of these is a 74kD electrophoretic species which can be resolved as two to three bands by SDS-PAGE. We have now selected a series of overlapping rat brain cDNAs encoding the 74-kD species. The deduced sequence of a full-length eDNA predicts a 72,753 D polypeptide which includes the amino acid sequences of nine peptides determined by NH2-terminal microsequencing. PCR performed on first strand rat brain eDNA together with the sequence of a partially matching tryptic peptide indicated the existence of at least three isoforms of the 74-kD cytoplasmic dynein subunit