A SLOW HOMOTETRAMERIC KINESIN-RELATED MOTOR PROTEIN PURIFIED FROM DROSOPHILA EMBRYOS

Pan-kinesin peptide antibodies (Cole, D. G., Cande, W. Z., Baskin, R. J., Skoufias, D. A., Hogan, C. J., and Scholey, J. M. (1992) J. Cell S ci. 101, 291-301; Sawin, K. E., Mitchinson, T J., and Wordeman, L. G. (1992) J. Cell Sci. 101, 303-313) were used to identify and isolate ki nesin-related proteins (KRPs) from Drosophila melanogaster embryonic c ytosol. These KRPs cosedimented with microtubules (MTs) polymerized fr om cytosol treated with AMP-PNP (adenyl-5'-yl imidodiphosphate), and o ne of them, KRP(130), was further purified from ATP eluates of the emb ryonic MTs. Purified KRP(130) behaves as a ho motetrameric complex com posed of four 130-kDa polypeptide subunits which displays a ''slow'' p lus-end directed motor activity capable of moving single MTs at 0.04 /- 0.01 mu m/s. The 130-kDa subunit of KRP(130) was tested for reactiv ity with monoclonal and polyclonal antibodies that are specific for va rious members of the kinesin superfamily. Results indicate that the KR P(130) subunit is related to Xenopus Eg5 (Sawin, K. E., Le Guellec, K. L., Philippe, M., Mitchinson, T. J. (1992) Nature 359, 540-543), a me mber of the BimC subfamily of kinesins. Therefore, KRP(130) appears to be the first Drosophila KRP, and the first member of the BimC subfami ly in any organism, to be purified from native tissue as a multimeric motor complex.