An IQGAP-like protein is involved in actin assembly together with Cdc42 in the sea urchin egg.
We isolated a gene homologous to human cdc42 (ucdc42) from a sea urchin cDNA library. The GTPgammaS-bound UCdc42 induced actin assembly in sea urchin egg extract. Proteins that are involved in this actin assembly system were searched using UCdc42-bound agarose beads. A 180-kDa protein (p180), which showed a homology to human IQGAPs, bound to the GTPgammaS-UCdc42 beads. Immunodepletion of p180 from the sea urchin egg extract abolished this actin assembly on the UCdc42 beads. Immunofluorescent localization of p180 was similar to that of the actin cytoskeleton in the egg cortex and it was concentrated in the cleavage furrow during cytokinesis. A possible role of p180 in actin assembly is discussed.
Division of Biology, Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo.
Yukako
Y
Nishimura
Issei
I
Mabuchi
D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002455:Cell Division; D003599:Cytoskeleton / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012617:Sea Urchins / Q000378:metabolism*; D016415:Sequence Alignment; D020764:cdc42 GTP-Binding Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020703:ras GTPase-Activating Proteins
D000199:Actins; C101203:IQ motif containing GTPase activating protein 1; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; D020703:ras GTPase-Activating Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D020764:cdc42 GTP-Binding Protein