Rab-protein geranylgeranyltransferase complex

Definition

Target type: cellularcomponent

An protein-containing complex which catalyzes of the transfer of a geranyl-geranyl group from geranylgeranyl pyrophosphate to a Rab protein. In mammals it is composed of an alpha and a beta subunit, and associates with an accessory protein Rep (Rab escort protein). [GOC:jl, PMID:11886217]

The Rab-protein geranylgeranyltransferase complex is a multimeric enzyme responsible for the post-translational modification of Rab GTPases. This complex comprises four subunits: Rab escort protein (REP), Rab geranylgeranyl transferase alpha (RGGT-alpha), Rab geranylgeranyl transferase beta (RGGT-beta), and the small GTPase Rab.

**REP** binds to Rab GTPases in their GDP-bound form and chaperones them to the catalytic subunit of the complex.

**RGGT-alpha** is a peripheral membrane protein and anchors the complex to membranes, likely through its interaction with phospholipids.

**RGGT-beta** is the catalytic subunit of the complex. It utilizes geranylgeranyl diphosphate (GGPP) as a substrate to attach two geranylgeranyl groups to a cysteine residue in the C-terminal CAAX motif of Rab GTPases.

**Rab GTPases** are small signaling proteins that regulate various cellular processes including membrane trafficking, exocytosis, and cytoskeletal dynamics. The geranylgeranylation of Rab proteins is crucial for their proper localization and function.

The complex undergoes a dynamic cycle of assembly and disassembly, allowing for efficient and regulated geranylgeranylation of Rab GTPases.

The Rab-protein geranylgeranyltransferase complex is localized in the cytoplasm and at the endoplasmic reticulum (ER) membrane. Its presence at the ER is essential for the initial geranylgeranylation of Rab proteins before they are transported to other cellular compartments.

**The cellular component of this complex includes the cytoplasm, endoplasmic reticulum membrane, and likely other cellular membranes where Rab GTPases function.**'
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Proteins (1)

Compounds (1)