Table 2

Proteins that interact with Rho-family guanosine 5′-triphosphatases

GTPase(s)EffectorFunctions/commentsReferences
Cdc42p120ACK Tyrosine kinase; phosphorylates NADPH-p47phox (Aspenstrom et al., 1996)
WASPWiskott-Aldrich Syndrome protein; binds Nck; may be involved in regulation of hematopoietic cell cytoskeleton(Aspenstrom et al., 1996; Quilliam et al., 1996; Symons et al., 1996)
RacPOR-1Partner of Rac; contains leucine-zipper; may mediate membrane ruffling(Van Aelst et al., 1996)
p67phox Component of phagocytic NADPH oxidase complex(Diekmann et al., 1994)
Cdc42 and RacMLK-3Mixed lineage kinase; may mediate Cdc42- and Rac-dependent activation of JNK/SAPK or p38/RK pathways(Teramotoet al., 1996a)
MEKK1May mediate Cdc42- and Rac-dependent activation of JNK/SAPK pathway(Fanger et al., 1997)
p65PAK Serine/threonine kinase homologous to yeast Ste20p; implicated in activation of p38/RK pathway and in regulation of actin organization(Manser et al., 1994; Sells et al., 1997; Zhang et al., 1995a)
p70S6K Ribosomal protein kinase; activated by mitogens and cell adhesion(Chou and Blenis, 1996; Malik and Parsons, 1996)
PI-3KImportant lipid kinase (generates 3′-phosphatidylinositols); involved in antiapoptotic signaling (through Akt/PKB); required for activation of p70S6K by some stimuli; implicated in PDGF-mediated activation of Rac(Franke et al., 1997; Nobes et al., 1995; Tolias et al., 1995; Zheng et al., 1994b)
RhoPKNAlso called PRK1 or 2; related to PKC; may regulate Rho-mediated gene expression(Amano et al., 1996b; Watanabe et al., 1996b)
Rhotekin, RhophilinFunction/activities unknown; Rho-binding domains have homology to that in PKN(Reidet al., 1996)
Rho kinaseAlso called ROKα; contains coiled-coil, leucine zipper, PH, and cysteine-rich domains; member of kinase family that includes myotonic dystrophy kinase and p160ROCK/ROKβ (which also binds Rho); involved in assembly of stress fibers/focal adhesions and in Rho-dependent regulation of MLC phosphorylation(Ishizaki et al., 1996; Kimura et al., 1996; Leung et al., 1995; Matsui et al., 1996)
MLCPMyosin light chain phosphatase; associates with Rho through myosin binding subunit; activity is inhibited by Rho kinase-mediated phosphorylation(Kimura et al., 1996)
Rho and RacCitronContains coiled-coil, leucine zipper, PH, and cysteine-rich domains(Madaule et al., 1995)
PI4P-5KPrincipal mediator of PI(4,5)P2 synthesis; binds GDP/GTP-bound forms of Rac/Rho, but activated only by GTP-bound; different isoforms may mediate Rac- and Rho-associated activity(Chong et al., 1994; Loijenset al., 1996; Ren et al., 1996; Tolias et al., 1995)