Domain

Coatomer, gamma subunit, appendage, Ig-like subdomain (IPR013040)

Short name: Coatomer_gsu_app_Ig-like-sub

Domain relationships

Description

Proteins synthesised on the ribosome and processed in the endoplasmic reticulum are transported from the Golgi apparatus to the trans-Golgi network (TGN), and from there via small carrier vesicles to their final destination compartment. This traffic is bidirectional, to ensure that proteins required to form vesicles are recycled. Vesicles have specific coat proteins (such as clathrin or coatomer) that are important for cargo selection and direction of transfer [PMID: 15261670]. While clathrin mediates endocytic protein transport, and transport from ER to Golgi, coatomers primarily mediate intra-Golgi transport, as well as the reverse Golgi to ER transport of dilysine-tagged proteins [PMID: 14690497]. For example, the coatomer COP1 (coat protein complex 1) is responsible for reverse transport of recycled proteins from Golgi and pre-Golgi compartments back to the ER, while COPII buds vesicles from the ER to the Golgi [PMID: 11208122]. Coatomers reversibly associate with Golgi (non-clathrin-coated) vesicles to mediate protein transport and for budding from Golgi membranes [PMID: 17041781]. Activated small guanine triphosphatases (GTPases) attract coat proteins to specific membrane export sites, thereby linking coatomers to export cargos. As coat proteins polymerise, vesicles are formed and budded from membrane-bound organelles. Coatomer complexes also influence Golgi structural integrity, as well as the processing, activity, and endocytic recycling of LDL receptors. In mammals, coatomer complexes can only be recruited by membranes associated to ADP-ribosylation factors (ARFs), which are small GTP-binding proteins. Coatomer complexes are hetero-oligomers composed of at least an alpha, beta, beta', gamma, delta, epsilon and zeta subunits.

This entry represents a beta-sandwich structural motif found in the appendage domain of the gamma subunit of coatomer complexes. This subdomain has an immunoglobulin-like beta-sandwich fold containing 7 strands in 2 beta-sheets in a Greek key topology [PMID: 14527408]. The appendage domain of the gamma coatomer subunit has a similar overall fold to the appendage domain of clathrin adaptors, and can also share the same motif-based cargo recognition and accessory factor recruitment mechanisms.

GO terms

Biological Process

GO:0006886 intracellular protein transport
GO:0016192 vesicle-mediated transport

Molecular Function

GO:0005198 structural molecule activity

Cellular Component

GO:0030126 COPI vesicle coat

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
Pfam
GENE3D