GARPkompleksi

GARPkompleksi, more commonly known as the GARP complex, is a conserved multisubunit tethering complex that operates in eukaryotic intracellular membrane trafficking. Its primary role is in retrograde transport to the Golgi apparatus, particularly at the trans-Golgi network (TGN), where it helps capture vesicles derived from endosomes and promotes their tethering and subsequent SNARE-mediated fusion with the Golgi membrane.

Composition: The complex is a heterotetramer formed by four subunits: VPS51, VPS52, VPS53, and VPS54 in mammals; equivalent names are Vps51, Vps52, Vps53, Vps54 in yeast. The subunits assemble into a stable complex that can bridge vesicles to the Golgi surface.

Localization and mechanism: GARP is anchored at the TGN and interacts with Rab GTPases and SNARE proteins, functioning as part of the tethering machinery that precedes membrane fusion. It works in coordination with other trafficking components to maintain Golgi organization and to ensure proper retrieval of Golgi-resident enzymes and recycled cargo.

Biological and clinical relevance: Proper GARP function is essential for efficient protein sorting and membrane traffic. Loss or impairment of GARP subunits in model organisms disrupts Golgi trafficking and cellular homeostasis. In humans, alterations in GARP components have been investigated in the context of developmental and neurological disorders, illustrating the complex's importance for cellular and organismal health.

History: GARP is described as part of a broader family of multisubunit tethering complexes that regulate vesicle docking at the Golgi. The name reflects its Golgi-associated retrograde transport function.