4j73
From Proteopedia
Crystal structure of beta'-COP/p25 complex
Structural highlights
Function[COPB2_YEAST] The coatomer is a cytosolic protein complex that binds to dilysine motifs and reversibly associates with Golgi non-clathrin-coated vesicles, which further mediate biosynthetic protein transport from the ER, via the Golgi up to the trans Golgi network. Coatomer complex is required for budding from Golgi membranes, and is essential for the retrograde Golgi-to-ER transport of dilysine-tagged proteins.[1] [TMED9_BOVIN] Appears to be involved in vesicular protein trafficking, mainly in the early secretory pathway. In COPI vesicle-mediated retrograde transport involved in the coatomer recruitment to membranes of the early secretory pathway. Increases coatomer-dependent activity of ARFGAP2. Thought to play a crucial role in the specific retention of p24 complexes in cis-Golgi membranes; specifically contributes to the coupled localization of TMED2 and TMED10 in the cis-Golgi network. May be involved in organization of intracellular membranes, such as of the ER-Golgi intermediate compartment and the Golgi apparatus. Involved in ER localization of PTPN2 (By similarity). Publication Abstract from PubMedCytoplasmic dilysine motifs on transmembrane proteins are captured by coatomer alpha-COP and beta'-COP subunits and packaged into COPI-coated vesicles for Golgi-to-ER retrieval. Numerous ER/Golgi proteins contain K(x)Kxx motifs, but the rules for their recognition are unclear. We present crystal structures of alpha-COP and beta'-COP bound to a series of naturally occurring retrieval motifs-encompassing KKxx, KxKxx and non-canonical RKxx and viral KxHxx sequences. Binding experiments show that alpha-COP and beta'-COP have generally the same specificity for KKxx and KxKxx, but only beta'-COP recognizes the RKxx signal. Dilysine motif recognition involves lysine side-chain interactions with two acidic patches. Surprisingly, however, KKxx and KxKxx motifs bind differently, with their lysine residues transposed at the binding patches. We derive rules for retrieval motif recognition from key structural features: the reversed binding modes, the recognition of the C-terminal carboxylate group which enforces lysine positional context, and the tolerance of the acidic patches for non-lysine residues. Rules for the recognition of dilysine retrieval motifs by coatomer.,Ma W, Goldberg J EMBO J. 2013 Mar 12. doi: 10.1038/emboj.2013.41. PMID:23481256[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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