ARHGEF7

Rho guanine nucleotide exchange factor 7 is a protein that in humans is encoded by the ARHGEF7 gene.

ARHGEF7
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1BY1, 1ZSG, 2L3G
Identifiers
Aliases	ARHGEF7, BETA-PIX, COOL-1, COOL1, Nbla10314, P50, P50BP, P85, P85COOL1, P85SPR, PAK3, PIXB, Rho guanine nucleotide exchange factor 7
External IDs	OMIM: 605477 MGI: 1860493 HomoloGene: 2895 GeneCards: ARHGEF7
Gene location (Human) Chr. Chromosome 13 (human) Band 13q34 Start 111,114,559 bp End 111,305,737 bp
Gene location (Mouse) Chr. Chromosome 8 (mouse) Band 8|8 A1.1 Start 11,727,721 bp End 11,835,219 bp
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in middle temporal gyrus sural nerve cerebellar vermis right coronary artery subcutaneous adipose tissue left coronary artery skin of abdomen ascending aorta prefrontal cortex right lung Top expressed in cerebellar vermis external carotid artery internal carotid artery barrel cortex endocardial cushion ganglionic eminence atrium atrioventricular valve piriform cortex superior frontal gyrus More reference expression data BioGPS More reference expression data
Gene ontology Molecular function protein binding guanyl-nucleotide exchange factor activity protein kinase binding Cellular component cytoplasm cytosol cell projection focal adhesion ruffle plasma membrane cell junction neuronal cell body cell cortex neuron projection storage vacuole lamellipodium intracellular anatomical structure Biological process regulation of GTP binding intracellular signal transduction negative regulation of epidermal growth factor receptor signaling pathway positive regulation of lamellipodium morphogenesis Golgi organization ephrin receptor signaling pathway nervous system development focal adhesion assembly positive regulation of substrate adhesion-dependent cell spreading positive regulation of growth hormone secretion hematopoietic progenitor cell differentiation positive regulation of apoptotic process positive regulation of protein binding regulation of Rho protein signal transduction regulation of small GTPase mediated signal transduction positive regulation of fibroblast migration signal transduction lamellipodium assembly positive regulation of GTPase activity G protein-coupled receptor signaling pathway Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 8874 54126 Ensembl ENSG00000102606 ENSMUSG00000031511 UniProt Q14155 Q9ES28 RefSeq (mRNA) NM_001113511 NM_001113512 NM_001113513 NM_003899 NM_145735 NM_001320851 NM_001320852 NM_001320853 NM_001320854 NM_001330597 NM_001330598 NM_001354046 NM_001354047 NM_001354048 NM_001354049 NM_001354050 NM_001354051 NM_001354052 NM_001354053 NM_001354054 NM_001354055 NM_001354056 NM_001354057 NM_001354058 NM_001354059 NM_001354060 NM_001354061 NM_001113517 NM_001113518 NM_017402 NM_001372321 NM_001372322 NM_001372323 NM_001372324 NM_001372325 NM_001372326 RefSeq (protein) NP_001106983 NP_001106984 NP_001106985 NP_001307780 NP_001307781 NP_001307782 NP_001307783 NP_001317526 NP_001317527 NP_003890 NP_663788 NP_001340975 NP_001340976 NP_001340977 NP_001340978 NP_001340979 NP_001340980 NP_001340981 NP_001340982 NP_001340983 NP_001340984 NP_001340985 NP_001340986 NP_001340987 NP_001340988 NP_001340989 NP_001340990 NP_001106985.1 NP_003890.1 NP_001307780.1 NP_001106989 NP_001106990 NP_059098 NP_001359250 NP_001359251 NP_001359252 NP_001359253 NP_001359254 NP_001359255 Location (UCSC) Chr 13: 111.11 – 111.31 Mb Chr 8: 11.73 – 11.84 Mb PubMed search
Wikidata
View/Edit Human View/Edit Mouse

ARHGEF7 is commonly known as the p21-activated protein kinase exchange factor beta (beta-PIX or βPIX), because it was identified by binding to p21-activated kinase (PAK) and also contains a guanine nucleotide exchange factor domain.

Domains and functions

βPIX is a multidomain protein that functions both as a signaling scaffold protein and as an enzyme. βPIX shares this domain structure and signaling function with the highly similar ARHGEF6/αPIX protein.

βPIX undergoes extensive alternative splicing to generate multiple variant proteins containing or lacking particular protein domains. Adult forms all lack the amino terminal CH domain, and the two major adult variants have alternate carboxyl terminal region (termed β1 and β2): β1 forms contain the coiled-coil trimerization domain and the PDZ-target motif for binding to PDZ proteins (see below), while β2 forms lack both domains and their corresponding functions.

βPIX contains a central DH/PH RhoGEF domain that functions as a guanine nucleotide exchange factor (GEF) for small GTPases of the Rho family, and specifically Rac and Cdc42. Like other GEFs, βPIX can promote both release of GDP from an inactive small GTP-binding protein and binding of GTP to promote its activation. Signaling scaffolds bind to specific partners to promote efficient signal transduction by arranging sequential elements of a pathway near each other to facilitate interaction/information transfer, and also by holding these partner protein complexes in specific locations within the cell to promote local or regional signaling. In the case of βPIX, its SH3 domain binds to partner proteins with appropriate polyproline motifs, and particularly to group I p21-activated kinases (PAKs) (PAK1, PAK2 and PAK3). PAK is bound to the βPIX SH3 domain in the inactive state, and activated Rac1 or Cdc42 binding to this PAK stimulates its protein kinase activity leading to downstream target protein phosphorylation; since βPIX can activate the “p21’’ small GTPases Rac1 or Cdc42 through its GEF activity, this βPIX/PAK/Rac complex exemplifies a scaffolding function.

Structurally, βPIX assembles as a trimer through a carboxyl-terminal coiled-coil domain that is present in the major carboxyl terminal splice variant β1, and further interacts with dimers of GIT1 or GIT2 through a nearby GIT-binding domain to form oligomeric GIT-PIX complexes. Through this GIT-PIX complex, the scaffolding function of βPIX is amplified by also being able to hold GIT partners in proximity to βPIX partners. In contrast, β2 carboxyl terminal variants lack this coiled-coil region and are predicted to be unable to trimerize. The major carboxyl terminal variant β1 also has a PDZ domain binding target motif that binds to the PDZ domains in SHANK1, scribble, and SNX27 proteins. Some splice variants of βPIX contain an amino-terminal Calponin Homology (CH) domain whose functions remain relatively poorly defined, but may interacts with parvin/affixin family proteins. βPIX variants with this extended amino terminal CH domain are most highly expressed early in development, but appear rare after birth.

Interactions

βPIX has been reported to interact with over 120 proteins.

Major interacting proteins include:

• Itself, or the highly-related ARHGEF6/αPIX via a trimeric coiled-coil interaction.
• GIT1 or GIT2 dimers via GIT-binding domain.
• p21-activated kinases (PAKs) 1, 2 and 3 via SH3 domain.
• c-Cbl via SH3 domain.
• Rho family GTP-binding protein family members Rac1 and Cdc42, activated via DHPH RhoGEF domain.
• The neuronal synapse adaptors SHANK1, SHANK2, and SHANK3 via PDZ
• Scribble via PDZ
• SNX27 via PDZ

See also

• Rho family of GTPases
• Scaffold protein
• Guanine nucleotide exchange factor

Further reading

• Turner CE, Brown MC, Perrotta JA, Riedy MC, Nikolopoulos SN, McDonald AR, Bagrodia S, Thomas S, Leventhal PS (1999). "Paxillin LD4 motif binds PAK and PIX through a novel 95-kD ankyrin repeat, ARF-GAP protein: A role in cytoskeletal remodeling". J. Cell Biol. 145 (4): 851–63. doi:10.1083/jcb.145.4.851. PMC 2133183. PMID 10330411.
• Bagrodia S, Bailey D, Lenard Z, Hart M, Guan JL, Premont RT, Taylor SJ, Cerione RA (1999). "A tyrosine-phosphorylated protein that binds to an important regulatory region on the cool family of p21-activated kinase-binding proteins". J. Biol. Chem. 274 (32): 22393–400. doi:10.1074/jbc.274.32.22393. PMID 10428811.
• Premont RT, Claing A, Vitale N, Perry SJ, Lefkowitz RJ (2000). "The GIT family of ADP-ribosylation factor GTPase-activating proteins. Functional diversity of GIT2 through alternative splicing". J. Biol. Chem. 275 (29): 22373–80. doi:10.1074/jbc.275.29.22373. PMID 10896954.
• Ku GM, Yablonski D, Manser E, Lim L, Weiss A (2001). "A PAK1-PIX-PKL complex is activated by the T-cell receptor independent of Nck, Slp-76 and LAT". EMBO J. 20 (3): 457–65. doi:10.1093/emboj/20.3.457. PMC 133476. PMID 11157752.
• Koh CG, Tan EJ, Manser E, Lim L (2002). "The p21-activated kinase PAK is negatively regulated by POPX1 and POPX2, a pair of serine/threonine phosphatases of the PP2C family". Curr. Biol. 12 (4): 317–21. doi:10.1016/S0960-9822(02)00652-8. PMID 11864573.
• Brown MC, West KA, Turner CE (2002). "Paxillin-dependent paxillin kinase linker and p21-activated kinase localization to focal adhesions involves a multistep activation pathway". Mol. Biol. Cell. 13 (5): 1550–65. doi:10.1091/mbc.02-02-0015. PMC 111126. PMID 12006652.
• Shin EY, Shin KS, Lee CS, Woo KN, Quan SH, Soung NK, Kim YG, Cha CI, Kim SR, Park D, Bokoch GM, Kim EG (2003). "Phosphorylation of p85 beta PIX, a Rac/Cdc42-specific guanine nucleotide exchange factor, via the Ras/ERK/PAK2 pathway is required for basic fibroblast growth factor-induced neurite outgrowth". J. Biol. Chem. 277 (46): 44417–30. doi:10.1074/jbc.M203754200. PMID 12226077.
• Rosenberger G, Jantke I, Gal A, Kutsche K (2003). "Interaction of alphaPIX (ARHGEF6) with beta-parvin (PARVB) suggests an involvement of alphaPIX in integrin-mediated signaling". Hum. Mol. Genet. 12 (2): 155–67. doi:10.1093/hmg/ddg019. PMID 12499396.
• Mignone F, Grillo G, Liuni S, Pesole G (2003). "Computational identification of protein coding potential of conserved sequence tags through cross-species evolutionary analysis". Nucleic Acids Res. 31 (15): 4639–45. doi:10.1093/nar/gkg483. PMC 169873. PMID 12888525.
• Yamamoto Y, Fujimoto Y, Arai R, Fujie M, Usami S, Yamada T (2003). "Retrotransposon-mediated restoration of Chlorella telomeres: accumulation of Zepp retrotransposons at termini of newly formed minichromosomes". Nucleic Acids Res. 31 (15): 4646–53. doi:10.1093/nar/gkg490. PMC 169880. PMID 12888526.
• Flanders JA, Feng Q, Bagrodia S, Laux MT, Singavarapu A, Cerione RA (2003). "The Cbl proteins are binding partners for the Cool/Pix family of p21-activated kinase-binding proteins". FEBS Lett. 550 (1–3): 119–23. doi:10.1016/S0014-5793(03)00853-6. PMID 12935897. S2CID 46540220.
• Shin EY, Woo KN, Lee CS, Koo SH, Kim YG, Kim WJ, Bae CD, Chang SI, Kim EG (2004). "Basic fibroblast growth factor stimulates activation of Rac1 through a p85 betaPIX phosphorylation-dependent pathway". J. Biol. Chem. 279 (3): 1994–2004. doi:10.1074/jbc.M307330200. PMID 14557270.
• Lim CS, Kim SH, Jung JG, Kim JK, Song WK (2004). "Regulation of SPIN90 phosphorylation and interaction with Nck by ERK and cell adhesion". J. Biol. Chem. 278 (52): 52116–23. doi:10.1074/jbc.M310974200. PMID 14559906.

External links

• ARHGEF7 Info with links in the Cell Migration Gateway
• Human ARHGEF7 genome location and ARHGEF7 gene details page in the UCSC Genome Browser.
• Human PAK3 genome location and PAK3 gene details page in the UCSC Genome Browser.