What is the function of Rab proteins?

Rab proteins are small guanosine triphosphatases which regulate protein transport along the endocytic and exocytic pathways in all cell types. Rabs participate in vesicle budding, membrane fusion, and interactions with the cytoskeleton.

What is the role of Rab Gtpase in the process?

Rab GTPases regulate many steps of membrane trafficking, including vesicle formation, vesicle movement along actin and tubulin networks, and membrane fusion. These processes make up the route through which cell surface proteins are trafficked from the Golgi to the plasma membrane and are recycled.

What do Rab effectors do?

Most functions of Rab GTPases and their effectors are related to vesicular traffic between a donor and an acceptor compartment, and it is interesting to note that distinct Rab effectors are involved in the sorting of cargo into budding vesicles, vesicle uncoating or vesicle motility along actin filaments or …

How are Rab proteins activated?

A guanine nucleotide exchange factor (GEF) catalyzes exchange of GDP for GTP to activate the Rab. The GTP-bound Rab interacts with effector proteins that mediate membrane traffic in the pathway regulated by its associated Rab.

What is the Rab cycle?

Rabs belong to the family of small GTPases that exert their regulatory role by acting as molecular switches. They cycle between an active GTP-bound and an inactive GDP-bound form, which is termed the “GTPase cycle”.

Where are Rab proteins found?

Rab proteins form the largest branch of the Ras superfamily of GTPases. They are localized to the cytoplasmic face of organelles and vesicles involved in the biosynthetic/secretory and endocytic pathways in eukaryotic cells.

What is Rab Gene?

The Rab family is part of the Ras superfamily of small GTPases. There are at least 60 Rab genes in the human genome, and a number of Rab GTPases are conserved from yeast to humans. Through their effectors, Rab GTPases regulate vesicle formation, actin- and tubulin-dependent vesicle movement, and membrane fusion.

What is a Rab gap?

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.

Is HTT a Rab effector?

The Htt–HAP40 complex is a novel Rab5 effector. Affinity chromatography revealed several downstream effectors of the small GTPase Rab5 (Christoforidis et al. 1999). Therefore, we investigated the function of HAP40 and Htt with respect to Rab5.

Who discovered Rab?

Dieter Gallwitz was the first to discover a yeast-encoded member of the Rab family in the 1980s, when DNA sequencing was just beginning to be widely adopted and required significant effort.

How many members does the Rab have?

The Rab Family Rab proteins comprise the largest subgroup within the Ras superfamily and consist of over 60 mammalian members.

What is ran GTPase?

The Ran (Ran-related or Ras-like nuclear) protein is the single member of the Ran subfamily, and the most abundant small GTPase in the cell. Like the other small GTPases, Ran functions as a molecular switch, converting between the active GTP-bound and inactive GDP-bound conformations.