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Gene Review

Rab27a  -  RAB27A, member RAS oncogene family

Mus musculus

Synonyms: 2210402C08Rik, 2410003M20Rik, 4933437C11Rik, Ras-related protein Rab-27A, ash
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Disease relevance of Rab27a


High impact information on Rab27a


Biological context of Rab27a


Anatomical context of Rab27a

  • Genetic studies suggest that these genes function in the same or overlapping pathways and are supported by biochemical studies showing that d encodes an actin-based melanosome transport motor, MyoVa, whereas ash encodes Rab27a, a protein that localizes to the melanosome and is postulated to serve as the MyoVa receptor [11].
  • The limited number of Rab proteins with defective membrane association in gm/gm megakaryocytes prominently includes Rab27a and Rab27b [12].
  • Rab27a and myosin VIIa are likely to be required for association with and movement through the apical actin cytoskeleton, which is a prerequisite for entry into the apical processes [7].
  • In ashen (Rab27a null) mice RPE, melanosomes are unable to move beyond the adherens junction axis and do not enter apical processes, suggesting that Rab27a regulates melanosome distribution in the RPE [7].
  • These results suggest that Rab27a interacts with different classes of effector proteins in melanocytes and cytotoxic T lymphocytes [13].

Associations of Rab27a with chemical compounds

  • Substitutions introduced at the 73 position, including the leucine residue present in Ras, did not restore Rab27a protein functions [14].
  • Analyses by immunofluorescence, immunoelectron microscopy, and sucrose density gradient subcellular fractionation showed that Rab27a and granuphilin are localized on the membrane of insulin granules [15].
  • We show here that the introduction of a proline residue in the alpha 4 (Ala152Pro) or beta 5 (Leu130Pro) loop, observed in 2 of these spontaneous mutants, dramatically affects both guanosine triphosphate (GTP) and guanosine diphosphate (GDP) nucleotide-binding activity of Rab27a, probably by disrupting protein folding [14].
  • Taken together, our results indicate that interaction of GDP-Rab27a and coronin 3 is important in stimulus-endocytosis coupling, and that GTP- and GDP-Rab27a regulates insulin membrane recycling at the distinct stages [16].
  • Recombinant Rab3GEP exhibits guanine nucleotide exchange activity against Rab27a and Rab27b in vitro, in addition to its previously documented activity against Rab3 [17].

Other interactions of Rab27a


Analytical, diagnostic and therapeutic context of Rab27a

  • Semi-quantitative immunoblotting suggests that mass action, i.e. the amount of Rab27a relative to other Rabs, is unlikely to be a factor as the expression level of Rab27a is similar to other Rabs not affected in these diseases [21].


  1. Rab27a mediates the tight docking of insulin granules onto the plasma membrane during glucose stimulation. Kasai, K., Ohara-Imaizumi, M., Takahashi, N., Mizutani, S., Zhao, S., Kikuta, T., Kasai, H., Nagamatsu, S., Gomi, H., Izumi, T. J. Clin. Invest. (2005) [Pubmed]
  2. Rab27a regulates the peripheral distribution of melanosomes in melanocytes. Hume, A.N., Collinson, L.M., Rapak, A., Gomes, A.Q., Hopkins, C.R., Seabra, M.C. J. Cell Biol. (2001) [Pubmed]
  3. The regulation of platelet-dense granules by Rab27a in the ashen mouse, a model of Hermansky-Pudlak and Griscelli syndromes, is granule-specific and dependent on genetic background. Novak, E.K., Gautam, R., Reddington, M., Collinson, L.M., Copeland, N.G., Jenkins, N.A., McGarry, M.P., Swank, R.T. Blood (2002) [Pubmed]
  4. Mouse genetic corneal disease resulting from transgenic insertional mutagenesis. Ramalho, J.S., Gregory-Evans, K., Huxley, C., Seabra, M.C. The British journal of ophthalmology. (2004) [Pubmed]
  5. Delivering the kiss of death. Trambas, C.M., Griffiths, G.M. Nat. Immunol. (2003) [Pubmed]
  6. Identification of an organelle receptor for myosin-Va. Wu, X.S., Rao, K., Zhang, H., Wang, F., Sellers, J.R., Matesic, L.E., Copeland, N.G., Jenkins, N.A., Hammer, J.A. Nat. Cell Biol. (2002) [Pubmed]
  7. The role of Rab27a in the regulation of melanosome distribution within retinal pigment epithelial cells. Futter, C.E., Ramalho, J.S., Jaissle, G.B., Seeliger, M.W., Seabra, M.C. Mol. Biol. Cell (2004) [Pubmed]
  8. Rab7 and Rab27a control two motor protein activities involved in melanosomal transport. Jordens, I., Westbroek, W., Marsman, M., Rocha, N., Mommaas, M., Huizing, M., Lambert, J., Naeyaert, J.M., Neefjes, J. Pigment Cell Res. (2006) [Pubmed]
  9. Characterization of the molecular defects in Rab27a, caused by RAB27A missense mutations found in patients with Griscelli syndrome. Bahadoran, P., Busca, R., Chiaverini, C., Westbroek, W., Lambert, J., Bille, K., Valony, G., Fukuda, M., Naeyaert, J.M., Ortonne, J.P., Ballotti, R. J. Biol. Chem. (2003) [Pubmed]
  10. Rab27a is required for regulated secretion in cytotoxic T lymphocytes. Stinchcombe, J.C., Barral, D.C., Mules, E.H., Booth, S., Hume, A.N., Machesky, L.M., Seabra, M.C., Griffiths, G.M. J. Cell Biol. (2001) [Pubmed]
  11. Mutations in Mlph, encoding a member of the Rab effector family, cause the melanosome transport defects observed in leaden mice. Matesic, L.E., Yip, R., Reuss, A.E., Swing, D.A., O'Sullivan, T.N., Fletcher, C.F., Copeland, N.G., Jenkins, N.A. Proc. Natl. Acad. Sci. U.S.A. (2001) [Pubmed]
  12. A role for Rab27b in NF-E2-dependent pathways of platelet formation. Tiwari, S., Italiano, J.E., Barral, D.C., Mules, E.H., Novak, E.K., Swank, R.T., Seabra, M.C., Shivdasani, R.A. Blood (2003) [Pubmed]
  13. The leaden gene product is required with Rab27a to recruit myosin Va to melanosomes in melanocytes. Hume, A.N., Collinson, L.M., Hopkins, C.R., Strom, M., Barral, D.C., Bossi, G., Griffiths, G.M., Seabra, M.C. Traffic (2002) [Pubmed]
  14. Biochemical and functional characterization of Rab27a mutations occurring in Griscelli syndrome patients. Menasche, G., Feldmann, J., Houdusse, A., Desaymard, C., Fischer, A., Goud, B., de Saint Basile, G. Blood (2003) [Pubmed]
  15. The Rab27a/granuphilin complex regulates the exocytosis of insulin-containing dense-core granules. Yi, Z., Yokota, H., Torii, S., Aoki, T., Hosaka, M., Zhao, S., Takata, K., Takeuchi, T., Izumi, T. Mol. Cell. Biol. (2002) [Pubmed]
  16. The GDP-dependent Rab27a effector coronin 3 controls endocytosis of secretory membrane in insulin-secreting cell lines. Kimura, T., Kaneko, Y., Yamada, S., Ishihara, H., Senda, T., Iwamatsu, A., Niki, I. J. Cell. Sci. (2008) [Pubmed]
  17. Rab3GEP is the non-redundant guanine nucleotide exchange factor for Rab27a in melanocytes. Figueiredo, A.C., Wasmeier, C., Tarafder, A.K., Ramalho, J.S., Baron, R.A., Seabra, M.C. J. Biol. Chem. (2008) [Pubmed]
  18. Role of myosin VIIa and Rab27a in the motility and localization of RPE melanosomes. Gibbs, D., Azarian, S.M., Lillo, C., Kitamoto, J., Klomp, A.E., Steel, K.P., Libby, R.T., Williams, D.S. J. Cell. Sci. (2004) [Pubmed]
  19. The acroplaxome is the docking site of Golgi-derived myosin Va/Rab27a/b- containing proacrosomal vesicles in wild-type and Hrb mutant mouse spermatids. Kierszenbaum, A.L., Tres, L.L., Rivkin, E., Kang-Decker, N., van Deursen, J.M. Biol. Reprod. (2004) [Pubmed]
  20. Granuphilin molecularly docks insulin granules to the fusion machinery. Gomi, H., Mizutani, S., Kasai, K., Itohara, S., Izumi, T. J. Cell Biol. (2005) [Pubmed]
  21. Multiple factors contribute to inefficient prenylation of Rab27a in Rab prenylation diseases. Larijani, B., Hume, A.N., Tarafder, A.K., Seabra, M.C. J. Biol. Chem. (2003) [Pubmed]
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