View source for Guanine nucleotide exchange factor



==Overview==
'''Guanine nucleotide exchange factor''' (or guanine exchange protein) (GEFs) is implicated in addressing system of [[vesicular transport]]. For example, [[Rab (G-protein)|Rab]] is [[GDP]]-bound and inactive in the [[cytosol]] before contact with GEF. The membrane-bound GEF catalyses the removal of GDP and GDI (GDP dissociation inhibitor) and their replacement with [[Guanosine triphosphate|GTP]]. This allows the Rab protein to bind budding [[vesicles]] (e.g., [[clathrin]]-coated vesicles). Un-coating of the vesicle allows an interaction between Rab and Rab effector (at the target site), which aids [[SNARE]] protein interactions.

==Examples of GEFs==

*[[Son of sevenless|SOS]] - Son of Sevenless is a GEF that is important in the cell growth-regulatory [[MAPK/ERK pathway]].

*[[eIF-2]]b - The eukaryotic initiation factor 2b regenerates eIF-2a for an additional cycle in protein synthesis initiation, i.e., its binding to the Met-t-RNA.

*[[Ras-GRF1]]

*[[G protein-coupled receptor]]s function as GEFs for their cognate [[G protein]]s.

* [[Kalirin]]

==See also==
* [[nucleotide exchange factor]]
* [[guanine]]
{{GTP-binding protein regulators}}

[[Category:GTP-binding protein regulators]]

[[de:GTP-Austauschfaktor]]
{{WH}}
{{WikiDoc Sources}}