The GIT/PIX complex: an oligomeric assembly of GIT family ARF GTPase-activating proteins and PIX family Rac1/Cdc42 guanine nucleotide exchange factors.
GIT proteins are GTPase-activating proteins (GAPs) for ADP-ribosylation factor (ARF) small GTP-binding proteins, and interact with the PIX family of Rac1/Cdc42 guanine nucleotide exchange factors. GIT and PIX transiently localize p21-activated protein kinases (PAKs) to remodeling focal adhesions through binding to paxillin. To understand the role of these interactions, the association of GIT and PIX proteins was examined in detail. Two separable binding interactions link GIT and PIX proteins, GIT and PIX proteins each dimerize and a beta-PIX fragment containing the GIT-binding region failed to inhibit the association of the GIT and PIX proteins. Endogenous GIT and PIX co-fractionate at a very high molecular size. Purified 6xHis-tagged beta-PIX from Sf9 cells co-expressing untagged GIT1 yields recombinant GIT1/beta-PIX complexes that have equal amounts of beta-PIX and GIT1 and co-fractionate at the same large size as native GIT/PIX complexes. Thus, GIT and PIX proteins are tightly associated as a multimeric nexus capable of linking together important signaling molecules, including PAKs.
Premont
Richard T
RT
Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, NC 27710, USA. richard.premont@duke.educ
Perry
Stephen J
SJ
Schmalzigaug
Robert
R
Roseman
J Tyler
JT
Xing
Yanghui
Y
Claing
Audrey
A
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D000882:Haplorhini; D006801:Humans; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism; D016296:Mutagenesis; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors; D014162:Transfection; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
C576606:ARHGEF7 protein, human; D018797:Cell Cycle Proteins; C430213:GIT2 protein, human; D020690:GTPase-Activating Proteins; C485648:Git1 protein, rat; D020662:Guanine Nucleotide Exchange Factors; D046911:Macromolecular Substances; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein