title: Identification of a kinesin-like microtubule-based motor protein in Dictyostelium discoideum.
abstract: Dictyostelium discoideum, a unicellular eukaryote amenable to both biochemical and genetic dissection, provides an attractive system for studying microtubule-based transport. In this work, we have identified microtubule-based motor activities in Dictyostelium cell extracts and have partially purified a protein that induces microtubule translocation along glass surfaces. This protein, which sediments at approximately 9S in sucrose density gradients and is composed of a 105 kd polypeptide, generates anterograde movement along microtubules that is insensitive to 5 mM NEM (N-ethyl-maleimide) but sensitive to 200 microM vanadate, and has similar nucleotide-dependent microtubule binding properties to those of kinesins purified from mammals, sea urchin and Drosophila. This kinesin-like molecule from Dictyostelium, however, is immunologically distinct from bovine and squid neuronal kinesins and supports microtubule movement on glass at four-fold greater velocities (2.0 versus 0.5 microns/sec). Furthermore, AMP-PNP (adenylyl imidodiphosphate), which promotes attachment of previously characterized kinesins to microtubules, decreases the affinity of the Dictyostelium kinesin homolog for microtubules. Thus, an AMP-PNP-induced rigor binding may not be a characteristic of kinesins from lower eukaryotes.
authors.affiliation: Department of Pharmacology, University of California, San Francisco 94143.
authors.forename: G
authors.initials: G
authors.lastname: McCaffrey
authors.forename: R D
authors.initials: RD
authors.lastname: Vale
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002499:Centrifugation, Density Gradient; D003429:Cross Reactions; D049832:Decapodiformes; D004023:Dictyostelium / Q000032:analysis*; D005033:Ethylmaleimide / Q000494:pharmacology; D007106:Immune Sera; D016547:Kinesins; D008868:Microtubule Proteins / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D008870:Microtubules / Q000378:metabolism / Q000502:physiology; D009068:Movement; D014638:Vanadates / Q000494:pharmacology
chemical_list: D007106:Immune Sera; D008868:Microtubule Proteins; D014638:Vanadates; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D016547:Kinesins; D005033:Ethylmaleimide