Stimulation of phospholipase C-beta2 by the Rho GTPases Cdc42Hs and Rac1.
Neutrophils contain a soluble guanine-nucleotidebinding protein, made up of two components with molecular masses of 23 and 26 kDa, that mediates stimulation of phospholipase C-beta2 (PLCbeta2). We have identified the two components of the stimulatory heterodimer by amino acid sequencing as a Rho GTPase and the Rho guanine nucleotide dissociation inhibitor LyGDI. Using recombinant Rho GTPases and LyGDI, we demonstrate that PLCbeta2 is stimulated by guanosine 5'-O-(3-thiotriphosphate) (GTP[S])-activated Cdc42HsxLyGDI, but not by RhoAxLyGDI. Stimulation of PLCbeta2, which was also observed for GTP[S]-activated recombinant Rac1, was independent of LyGDI, but required C-terminal processing of Cdc42Hs/Rac1. Cdc42Hs/Rac1 also stimulated PLCbeta2 in a system made up of purified recombinant proteins, suggesting that this function is mediated by direct protein-protein interaction. The Cdc42Hs mutants F37A and Y40C failed to stimulate PLCbeta2, indicating that the Cdc42Hs effector site is involved in this interaction. The results identify PLCbeta2 as a novel effector of the Rho GTPases Cdc42Hs and Rac1, and as the first mammalian effector directly regulated by both heterotrimeric and low-molecular-mass GTP-binding proteins.
Illenberger
D
D
Department of Pharmacology and Toxicology, University of Ulm, 89069 Ulm, Germany.
Schwald
F
F
Pimmer
D
D
Binder
W
W
Maier
G
G
Dietrich
A
A
Gierschik
P
P
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006160:Guanosine Triphosphate / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism*; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000201:enzymology / Q000378:metabolism*; D054799:Phospholipase C beta; D011506:Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics; D017421:Sequence Analysis; D010738:Type C Phospholipases / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein
D018797:Cell Cycle Proteins; D020690:GTPase-Activating Proteins; D007527:Isoenzymes; D011506:Proteins; D011993:Recombinant Fusion Proteins; D006160:Guanosine Triphosphate; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein