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Gene Review

ARHGAP26  -  Rho GTPase activating protein 26

Homo sapiens

Synonyms: GRAF, GRAF1, GTPase regulator associated with focal adhesion kinase, KIAA0621, OPHN1L, ...
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Disease relevance of ARHGAP26


Psychiatry related information on ARHGAP26

  • Graf and D. L. Schacter (1985, Journal of Experimental Psychology: Learning, Memory and Cognition, 11, 501-518) [5].
  • Contrary to the theory of the homeostatic model of self-concept, i.e., the expectancy that engaging in anti-social or pro-social behavior results typically in shifts in the self-concept (Graf, 1968; Deitz, 1970 shifts did not occur [6].

High impact information on ARHGAP26

  • On the protein level, it is 90% homologous to the recently described chicken GRAF gene that functions as a GAP of RhoA in vivo and is thus a critical component of the integrin signaling transduction pathway [2].
  • We have isolated the human GRAF gene (for GTPase regulator associated with the focal adhesion kinase pp125(FAK)) [2].
  • We found point mutations within the GAP domain of the second GRAF allele in one patient [2].
  • GRAF encodes a member of the Rho family of the GTPase-activating protein (GAP) family [2].
  • In two additional patients we found an insertion of 52 or 74 bp within the GRAF cDNA that generates a reading frame shift followed by a premature stop codon [2].

Biological context of ARHGAP26

  • Based on these data we suggest that phosphorylation of Graf by MAP kinase or related kinases may be a mechanism by which growth factor signaling modulates Rho-mediated cytoskeletal changes in PC12 and perhaps other cells [7].
  • We examined the expression and regulation of Graf as a prelude to understanding the role of Graf in mediating signal transduction in vivo [7].
  • Microinjection of Graf cDNA into subconfluent Swiss 3T3 cells (in the presence of serum) has marked effects on cell shape and actin localization [8].
  • The Graf response was dependent on GAP activity, since injection of Graf cDNA containing point mutations in the GAP domain (R236Q or N351V) which block enzymatic activity, does not confer this phenotype [8].
  • In a 1981 study by Graf et al, glycemic control and motor and sensory nerve conduction velocities were evaluated in 18 patients with non-insulin-dependent diabetes before and after one, three, six, and 12 months of antihyperglycemic therapy [9].

Anatomical context of ARHGAP26

  • Graf expression causes clearing of stress fibers followed by formation of long actin based filopodial-like extensions [8].
  • To further substantiate these results we examined the effect of Graf over-expression on Rho-mediated neurite retraction in nerve growth factor (NGF)-differentiated PC12 cells [8].
  • The suppressed GRAF expression could be restored in leukaemia cell lines by treatment with a demethylating agent and an inhibitor of histone deacetylases [10].
  • In contrast to normal tissues, which tested negative for GRAF promoter methylation, 11 of 29 (38%) bone marrow samples from patients with acute myeloid leukaemia or myelodysplastic syndrome were positive [10].
  • Graf ligamentoplasty stabilizes the unstable segment through coaptation of bilateral facet joints [11].

Associations of ARHGAP26 with chemical compounds

  • We suggest that Graf may function to mediate cross talk between the tyrosine kinases such as FAK and the Rho family GTPase that control steps in integrin-initiated signaling events [12].
  • In addition, the mutation of serine 510 to alanine inhibited the epidermal growth factor-induced mobility shift of mutant Graf protein in vivo, consistent with serine 510 being the site of in vivo phosphorylation [7].
  • 1. The ability of myo-inositol polyphosphates to inhibit iron-catalysed hydroxyl radical formation was studied in a hypoxanthine/xanthine oxidase system [Graf, Empson and Eaton (1987) J. Biol. Chem. 262, 11647-11650] [13].
  • These effects of mucidin and strobilurin A are, however, qualitatively identical with those of myxothiazol, an antibiotic that inhibits respiration by binding to cytochrome b [Von Jagow, G., Ljungdahl, P. O., Graf, P., Ohnishi, T., & Trumpower, B. L. (1984) J. Biol. Chem. 259, 6319-6326] [14].
  • Such feedings may have been essential for producing the previous observation (Graf, Balsam, & Silver, 1985) that pecking develops normally if squab which have been separated from their parents are given a daily 20-min interaction with seed followed by an immediate return to their parents [15].

Other interactions of ARHGAP26

  • The full length of Graf2 contains a putative PH domain, a RhoGAP domain, and an SH3 domain as well as Graf [1].

Analytical, diagnostic and therapeutic context of ARHGAP26


  1. PKNbeta interacts with the SH3 domains of Graf and a novel Graf related protein, Graf2, which are GTPase activating proteins for Rho family. Shibata, H., Oishi, K., Yamagiwa, A., Matsumoto, M., Mukai, H., Ono, Y. J. Biochem. (2001) [Pubmed]
  2. The human GRAF gene is fused to MLL in a unique t(5;11)(q31;q23) and both alleles are disrupted in three cases of myelodysplastic syndrome/acute myeloid leukemia with a deletion 5q. Borkhardt, A., Bojesen, S., Haas, O.A., Fuchs, U., Bartelheimer, D., Loncarevic, I.F., Bohle, R.M., Harbott, J., Repp, R., Jaeger, U., Viehmann, S., Henn, T., Korth, P., Scharr, D., Lampert, F. Proc. Natl. Acad. Sci. U.S.A. (2000) [Pubmed]
  3. MLL/GRAF fusion in an infant acute monocytic leukemia (AML M5b) with a cytogenetically cryptic ins(5;11)(q31;q23q23). Panagopoulos, I., Kitagawa, A., Isaksson, M., Mörse, H., Mitelman, F., Johansson, B. Genes Chromosomes Cancer (2004) [Pubmed]
  4. Use of MLL/GRAF fusion mRNA for measurement of minimal residual disease during chemotherapy in an infant with acute monoblastic leukemia (AML-M5). Wilda, M., Perez, A.V., Bruch, J., Woessmann, W., Metzler, M., Fuchs, U., Borkhardt, A. Genes Chromosomes Cancer (2005) [Pubmed]
  5. Deficits in the implicit retention of new associations by alcoholic Korsakoff patients. Cermak, L.S., Bleich, R.P., Blackford, S.P. Brain and cognition. (1988) [Pubmed]
  6. Self-concept and delinquency proneness. Jones, F.R., Swain, M.T. Adolescence. (1977) [Pubmed]
  7. Characterization of graf, the GTPase-activating protein for rho associated with focal adhesion kinase. Phosphorylation and possible regulation by mitogen-activated protein kinase. Taylor, J.M., Hildebrand, J.D., Mack, C.P., Cox, M.E., Parsons, J.T. J. Biol. Chem. (1998) [Pubmed]
  8. Cytoskeletal changes induced by GRAF, the GTPase regulator associated with focal adhesion kinase, are mediated by Rho. Taylor, J.M., Macklem, M.M., Parsons, J.T. J. Cell. Sci. (1999) [Pubmed]
  9. Effects of glycemic control and aldose reductase inhibition on nerve conduction velocity. Pfeifer, M.A. Am. J. Med. (1985) [Pubmed]
  10. Characterisation of the GRAF gene promoter and its methylation in patients with acute myeloid leukaemia and myelodysplastic syndrome. Bojesen, S.E., Ammerpohl, O., Weinhäusl, A., Haas, O.A., Mettal, H., Bohle, R.M., Borkhardt, A., Fuchs, U. Br. J. Cancer (2006) [Pubmed]
  11. Rationale, biomechanics, and surgical indications for Graf ligamentoplasty. Kanayama, M., Hashimoto, T., Shigenobu, K. Orthop. Clin. North Am. (2005) [Pubmed]
  12. An SH3 domain-containing GTPase-activating protein for Rho and Cdc42 associates with focal adhesion kinase. Hildebrand, J.D., Taylor, J.M., Parsons, J.T. Mol. Cell. Biol. (1996) [Pubmed]
  13. Inhibition of iron-catalysed hydroxyl radical formation by inositol polyphosphates: a possible physiological function for myo-inositol hexakisphosphate. Hawkins, P.T., Poyner, D.R., Jackson, T.R., Letcher, A.J., Lander, D.A., Irvine, R.F. Biochem. J. (1993) [Pubmed]
  14. Mucidin and strobilurin A are identical and inhibit electron transfer in the cytochrome bc1 complex of the mitochondrial respiratory chain at the same site as myxothiazol. Von Jagow, G., Gribble, G.W., Trumpower, B.L. Biochemistry (1986) [Pubmed]
  15. Operant and Pavlovian contributions to the ontogeny of pecking in ring doves. Balsam, P.D., Graf, J.S., Silver, R. Developmental psychobiology. (1992) [Pubmed]
  16. Adjacent-segment morbidity after Graf ligamentoplasty compared with posterolateral lumbar fusion. Kanayama, M., Hashimoto, T., Shigenobu, K., Harada, M., Oha, F., Ohkoshi, Y., Tada, H., Yamamoto, K., Yamane, S. J. Neurosurg. (2001) [Pubmed]
  17. Ultrasonographic screening for developmental dysplasia of the hip in infants. Reproducibility of assessments made by radiographers. Roovers, E.A., Boere-Boonekamp, M.M., Geertsma, T.S., Zielhuis, G.A., Kerkhoff, A.H. The Journal of bone and joint surgery. British volume. (2003) [Pubmed]
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