ARHGEF7

Rho guanine nucleotide exchange factor 7 is a protein that in humans is encoded by the ARHGEF7 gene.[5][6][7][8]

ARHGEF7
Available structures
PDBOrtholog search: PDBe RCSB
Identifiers
AliasesARHGEF7, BETA-PIX, COOL-1, COOL1, Nbla10314, P50, P50BP, P85, P85COOL1, P85SPR, PAK3, PIXB, Rho guanine nucleotide exchange factor 7
External IDsOMIM: 605477 MGI: 1860493 HomoloGene: 2895 GeneCards: ARHGEF7
Gene location (Human)
Chr.Chromosome 13 (human)[1]
Band13q34Start111,114,559 bp[1]
End111,305,737 bp[1]
RNA expression pattern


More reference expression data
Orthologs
SpeciesHumanMouse
Entrez

8874

54126

Ensembl

ENSG00000102606

ENSMUSG00000031511

UniProt

Q14155

Q9ES28

RefSeq (mRNA)
RefSeq (protein)
Location (UCSC)Chr 13: 111.11 – 111.31 MbChr 8: 11.73 – 11.84 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

ARHGEF7 is commonly known as the p21-activated protein kinase exchange factor alpha (beta-PIX or βPIX), because it was identified by binding to p21-activated kinase (PAK) and also contains a guanine nucleotide exchange factor domain.[6]

Domains and functions

βPIX is a multidomain protein that functions both as a signaling scaffold protein and as an enzyme.[9] 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.[9] 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.[9]

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.[6] 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).[6] 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.[9] 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,[10] scribble,[11] and SNX27[12] 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. [13][9] βPIX variants with this extended amino terminal CH domain are most highly expressed early in development, but appear rare after birth.[9]

Interactions

βPIX has been reported to interact with over 120 proteins.[9][14]

Major interacting proteins include:

See also

References

  1. GRCh38: Ensembl release 89: ENSG00000102606 - Ensembl, May 2017
  2. GRCm38: Ensembl release 89: ENSMUSG00000031511 - Ensembl, May 2017
  3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. Oh WK, Yoo JC, Jo D, Song YH, Kim MG, Park D (July 1997). "Cloning of a SH3 domain-containing proline-rich protein, p85SPR, and its localization in focal adhesion". Biochemical and Biophysical Research Communications. 235 (3): 794–798. doi:10.1006/bbrc.1997.6875. PMID 9207241.
  6. Manser E, Loo TH, Koh CG, Zhao ZS, Chen XQ, Tan L, Tan I, Leung T, Lim L (July 1998). "PAK kinases are directly coupled to the PIX family of nucleotide exchange factors". Molecular Cell. 1 (2): 183–192. doi:10.1016/S1097-2765(00)80019-2. PMID 9659915.
  7. Bagrodia S, Taylor SJ, Jordon KA, Van Aelst L, Cerione RA (October 1998). "A novel regulator of p21-activated kinases". Journal of Biological Chemistry. 273 (37): 23633–23636. doi:10.1074/jbc.273.37.23633. PMID 9726964.
  8. "Entrez Gene: ARHGEF7 Rho guanine nucleotide exchange factor (GEF) 7".
  9. Zhou W, Li X, Premont RT (May 2016). "Expanding functions of GIT Arf GTPase-activating proteins, PIX Rho guanine nucleotide exchange factors and GIT-PIX complexes". Journal of Cell Science. 129 (10): 1963–1974. doi:10.1242/jcs.179465. PMC 6518221. PMID 27182061.
  10. Park E, Na M, Choi J, Kim S, Lee JR, Yoon J, Park D, Sheng M, Kim E (2003). "The Shank family of postsynaptic density proteins interacts with and promotes synaptic accumulation of the beta PIX guanine nucleotide exchange factor for Rac1 and Cdc42". J. Biol. Chem. 278 (21): 19220–9. doi:10.1074/jbc.M301052200. PMID 12626503.
  11. Audebert S, Navarro C, Nourry C, Chasserot-Golaz S, Lecine P, Bellaiche Y, Dupont JL, Premont RT, Sempere C, Strub JM, Van Dorsselaer A, Vitale N, Borg JP (June 2004). "Mammalian Scribble forms a tight complex with the betaPIX exchange factor". Current Biology. 14 (11): 987–995. doi:10.1016/j.cub.2004.05.051. PMID 15182672.
  12. Valdes JL, Tang J, McDermott MI, Kuo JC, Zimmerman SP, Wincovitch SM, Waterman CM, Milgram SL, Playford MP (November 2011). "Sorting nexin 27 protein regulates trafficking of a p21-activated kinase (PAK) interacting exchange factor (β-Pix)-G protein-coupled receptor kinase interacting protein (GIT) complex via a PDZ domain interaction". Journal of Biological Chemistry. 286 (45): 39403–39416. doi:10.1074/jbc.M111.260802. PMC 3234764. PMID 21926430.
  13. 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". Human Molecular Genetics. 12 (2): 155–167. doi:10.1093/hmg/ddg019. PMID 12499396.
  14. "ARHGEF7 Result Summary".

Further reading



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