MADD exchanges GTP for GDP on RAB27

Stable Identifier
Reaction [transition]
Homo sapiens
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Vertebrate RAB27 exists in two isoforms, RAB27A and RAB27B, with overlapping but distinct functions in trafficking to melanosomes, secretory granules and platelets (Kondo et al, 2006; Figueiredo et al, 2008; Tarafder et al, 2011; reviewed in Fukuda et al, 2013). Studies in nematodes and vertebrates have identified MADD as a RAB27 GEF required for its activity (Mahoney et al, 2006; Tarafder et al, 2011; Yoshimura et al, 2010). Interaction of RAB27:GDP with its GEFs promotes release of GDP, allowing GTP to bind, and precludes the interaction of RAB27 with GDI and CHM proteins.

Literature References
PubMed ID Title Journal Year
21554507 Rab27a targeting to melanosomes requires nucleotide exchange but not effector binding

Seabra, MC, Wasmeier, C, Figueiredo, AC, Tarafder, AK, Ramalho, JS, Orihara, A, Hume, AN, Booth, AE

Traffic 2011
18559336 Rab3GEP is the non-redundant guanine nucleotide exchange factor for Rab27a in melanocytes

Seabra, MC, Wasmeier, C, Baron, RA, Figueiredo, AC, Tarafder, AK, Ramalho, JS

J. Biol. Chem. 2008
16880209 Constitutive GDP/GTP exchange and secretion-dependent GTP hydrolysis activity for Rab27 in platelets

Fukuda, M, Kondo, H, Horiuchi, H, Shirakawa, R, Higashi, T, Kita, T, Kawato, M

J. Biol. Chem. 2006
20937701 Family-wide characterization of the DENN domain Rab GDP-GTP exchange factors

Linford, A, Rigden, DJ, Barr, FA, Gerondopoulos, A, Yoshimura, S

J. Cell Biol. 2010
16571673 Regulation of synaptic transmission by RAB-3 and RAB-27 in Caenorhabditis elegans

Fukuda, M, Wang, ZW, Itoh, T, Nonet, ML, Hadwiger, G, Mahoney, TR, Luo, S, Vincent, R, Liu, Q

Mol. Biol. Cell 2006
23678941 Rab27 effectors, pleiotropic regulators in secretory pathways

Fukuda, M

Traffic 2013
Catalyst Activity

guanyl-nucleotide exchange factor activity of MADD [cytosol]

Orthologous Events
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