Fig. 1. Discovery and cloning of a novel class V myosin. (A) cDNA clones comprising the full coding sequence of human MYO5C. Combining the sequence of clones 2, 5 and 7 and EST 178419 results in 6839 bp of cDNA including 19 bp of 5'UTR, 5229 bp of coding sequence and 1591 bp of 3'UTR containing an Alu repeat and ending in a poly-A tail. Black shading indicates the sequenced portion of the clones. The locations of the mRNA probe, the His-tagged tail construct used to generate antibodies 199 and 200, and the GFP-tail construct are also depicted. Arrows indicate PCR primers used for amplification. (B) The three class V myosins in vertebrates. Note that the Myo5c tail lacks a PEST region but contains a small region similar to the alternatively spliced exon D mapped in Myo5a (Seperack et al., 1995). The human Myo5a sequence used here consists of a GenBank sequence (Y07759) into which we have inserted the 25 aa sequence of exon F. This Myo5a sequence thus includes all three alternatively spliced exons and will differ somewhat from actual splice forms in size and numbering. The diagrams of Myo5b and Myo5c are based on GenBank sequences U60416 and AF272390, respectively. (C) Predicted structure of the three class V myosins. Interestingly, the length of the initial segment of coiled-coil is predicted to be 30 nm for all three myosins.