Rab Gefs
Rab Gefs - Related Videos
01:14
Rab Proteins
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2023
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane. Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
01:25
Rab Cascades
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2023
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
11:28
Affinity Precipitation of Active Rho-GEFs Using a GST-tagged Mutant Rho Protein (GST-RhoA(G17A)) from Epithelial Cell Lysates
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Cited by 14 •
2012
The method presented here describes an assay to follow activation of RhoA specific GDP/GTP Exchange Factors (GEFs) in cultured cells by making use of a mutant RhoA GST fusion protein that has high affinity for activated GEFs. GEFs are precipitated from cell lysates, detected by Western blotting and quantified by densitometry.
02:14
GTPases and their Regulation
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2020
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins. Large G-proteins, also known...
04:27
Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae
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Cited by 27 •
2011
In this video, we describe a method for live cell imaging of asymmetrically dividing sensory organ progenitor cells and epidermal cells in intact Drosophila...
FAQs
A Rab GEF promotes the release of GDP from a Rab protein, creating an opportunity for GTP to bind. Because GTP is abundant in the cytosol, this exchange favors formation of the active Rab-GTP state. The resulting switch activation allows the Rab to recruit effector proteins and coordinate subsequent membrane-trafficking events.
Rab-GEF activity helps connect Rab activation with particular cellular membranes. Once activated, Rab-GTP recruits effector proteins to the membrane where it is present, supporting localized control of vesicle budding, transport, tethering, or fusion. This spatial organization contributes to organelle identity and helps prevent cargo from being delivered through an inappropriate trafficking route.
Rab GTPases act as molecular switches that alternate between inactive GDP-bound and active GTP-bound states, whereas Rab GEFs promote the nucleotide exchange needed to activate them. Their functions are therefore complementary: the GTPase provides the switch, while the exchange factor helps turn that switch on so downstream effectors can be recruited.
Examining Rab GEFs can reveal how cells organize the movement of material through secretory and endocytic pathways. Their activity links Rab activation with vesicle budding, transport, tethering, and fusion, allowing researchers to relate molecular switching to cargo delivery. This perspective helps explain how distinct organelles maintain coordinated trafficking relationships within the cell.
Disrupted Rab-GEF regulation can interfere with the activation pattern required for accurate membrane traffic. If Rab proteins are not properly switched into their active forms, effector recruitment and the events those effectors coordinate may be altered. Such defects can compromise organelle identity or cargo delivery, providing a mechanistic connection to disorders associated with membrane-trafficking disruption.
Rab GEFs provide a way to study how cells convert nucleotide-dependent molecular switching into organized transport behavior. Following their role connects biochemical events, such as GDP release and GTP binding, with larger cellular outcomes involving organelle maintenance and cargo movement. They therefore serve as an important context for investigating intracellular organization and trafficking-related disease mechanisms.