Rabs are GTP-binding proteins with conserved functions in membrane trafficking. They are regulated by a diverse group of structurally unrelated GDP-GTP exchange factors (GEFs), and a family of GTP-hydrolysis activating proteins (GAPs) containing the conserved TBC domain.

Aug 1, 2019 · Rab GTPases and their regulatory proteins play a crucial role in vesicle-mediated membrane trafficking. During vesicle membrane tethering Rab GTPases are activated by GEFs (guanine nucleotide exchange factors) and then inactivated …

In this review article, we provide the most up‐to‐date and comprehensive lists of GEFs, GAPs, effectors, and knockout phenotypes of mammalian Rabs and discuss recent findings in regard to their regulation and functions. Keywords: effector, GAP, GEF, knockout, membrane traffic, organelle, post‐translational modification, Rab small GTPases.

Aug 25, 2009 · Rab reactivation is catalyzed by guanine nucleotide exchange factors (GEFs) that speed release of Rab-bound GDP, permitting rebinding of cytosolic GTP. Active GTP-bearing Rabs are stabilized on membrane surfaces by binding to their cognate effector proteins (6).

Jul 15, 2009 · Rab GTPases are turned on and off by specific guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), respectively. Rab effectors come in many forms and range from...

Targeting of the Rab/REP (or Rab/GDI) complex to specific membranes is mediated by the interaction with a membrane-associated GEF, which stimulates GDP to GTP exchange of Rab; or in few cases by interaction with a GDF first, followed by GEF stimulated activation.

Jan 1, 2014 · Rab GEFs initiate a kinetic proofreading system for vesicle and target organelle membrane surfaces by promoting accumulation of active Rabs only at the required sites (Barr 2013). Rab GEFs and their target Rabs are therefore key determinants of membrane trafficking.

Rabs are the largest family of small GTPases and are master regulators of membrane trafficking. Following activation by guanine-nucleotide exchange factors (GEFs), each Rab binds a specific set of effector proteins that mediate the various downstream functions of that Rab.

In this review we give an overview of Rab proteins with a focus on the current understanding of their regulation by GEFs, GAPs and GDI.

Jan 7, 2019 · Guanine nucleotide exchange factors (GEFs) activate and consequently stabilize Rab substrates on membranes, thus implicating GEFs as the primary determinants of Rab localization. A competing hypothesis is that the Rab C-terminal hypervariable domain (HVD) serves as a subcellular targeting signal.