Action mechanisms and roles of small GTP-binding proteins

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RhoA and PKC activate synergistically the membrane-bound phospholipase D (PLD) in HL60. The Toxin B and C3 toxin treatments show involvement of CDC42 in PLD activation in RBL cells. PLD cDNAs were cloned from rat (Nozawa). (2) Rhabphilin-3A binds to synaptic vesicles via anchoring protein. A newly identified homolog Doc regulates exocytosis. A target protein of Rho1 is PKC in budding yeast (Takai). (3) Target proteins of Rho are PKN and p160^<PRCK>, rhophilin, rhotekin and citron. PKN and p160^<PRCK> are activated by GTP/Rho (Narumiya). (4) Expression of RhoA and RhoGDI decreases with age in rat prostate. The 20 kDa protein (H3 histone) is ADP-ribosylated (Ishibashi). (5) A factore inbolved in Raf1 activation is identified to be 14-3-3. A MAP kinase kinase (TAK1) acts in TGF-beta signaling (Matumoto). (6) Sar1p and E112K participate in vesicle transport between endoplasm reticulum and Golgi body in yeast. SAR1 from tobacco rescues SAR1 defective mutant of yeast (Nakano). (7) A arginine-specific ADP-ribosyl transferase cloned from chiken PMN ADP-ribosylates Arg^<28> in actin (Shimoyama). (8) A novel inhibitor (CKB-1055) inhibits S6 kinase in insulin signaling and exerts insulin-like action in glycogen metabolism (Hidaka.) (9) PLA_2 inhibitor blocks fusion of Golgi bodies and vesicles leading to inhibition of secretion. Brefeldin blocks vesicle formation (Ikehara). (10) Gene expression of thymidine transports greatly repressed in DnaA defective mutant of E.coli. (Sekimizu).