BIOCHEMICAL-CHARACTERIZATION OF RELATED MICROTUBULE PROTEINS IN DROSOPHILA-MELANOGASTER AND ADULT-RAT BRAIN

We describe the biochemical characteristics of three proteins isolated from Drosophila embryos and the rat brain. We refer to these proteins as DMAPs (Drosophila microtubule-associated proteins) since they were identified by monoclonal antibodies generated against microtubule pro tein (MTP) purified from Drosophila melanogaster embryos. DMAP-45 is a 45 kDa protein that binds microtubules in an ATP dependent manner. Pr eliminary biochemical evidence suggests that DMAP-45 may be an actin-r elated protein. DMAP-55 is a 55 kDa protein and based on its molecular weight and isoelectric point, may be a novel isoform of tubulin. DMAP -66 isa 66 kDa protein that binds strongly to microtubules in vitro an d has multiple isoforms. Analyses of proteins in rat brain tissue extr acts and purified rat brain MTP identified proteins of similar molecul ar weight and isoelectric points and are designated DMAP-45R, -55R and -66R. The presence of proteins with common biochemical properties in these widely divergent animal species suggests that they are related p roteins.