5h3j | pdb_00005h3j
Crystal structure of Grasp domain of Grasp55 complexed with the Golgin45 C-terminus
Structural highlights
Function[GORS2_MOUSE] Plays a role in assembly and membrane stacking of the Golgi cisternae, and in the process by which Golgi stacks reform after mitotic breakdown. May regulate the intracellular transport and presentation of a defined set of transmembrane proteins, such as transmembrane TGFA.[1] [GO45_MOUSE] Required for normal Golgi structure and for protein transport from the endoplasmic reticulum (ER) through the Golgi apparatus to the cell surface. Publication Abstract from PubMedGolgin45 is required for normal Golgi structure and the transportation of protein from the ER. It forms a specific complex with GRASP55 in vivo Little is known regarding the molecular details of this interaction and its structural role in stacking of the Golgi complex. Here, we present the crystal structure of the GRASP domains of GRASP55 in complex with the Golgin45 C-terminal peptide, determined at 1.33 A resolution. Similar to the structure of GRASP65 bound to GM130 reported recently, this structure reveals more than one interacting site and involves both PDZ1 and PDZ2 domains of the GRASP simultaneously. The C-terminal peptides of Golgin45 and GM130 present a conserved PDZ domain binding motif sequence and recognize the canonical PDZ-peptide binding groove of the PDZ1 domains of GRASP55 and GRASP65. A main difference in this recognition process resides in a structural rearrangement of GRASP65-GM130 that does not occur for the GRASP55-Golgin45 complex. The binding site at the cleft between the PDZ1 and PDZ2 domains of GRASP65 is dominated by hydrophobic interactions with GM130 that are not observed in the GRASP55-Golgin45 complex. In addition, a unique zinc finger structure is revealed in the GRASP55-Golgin45 complex crystal structure. Mutagenesis experiments support these structural observations and demonstrate that two of these sites are required to form a stable complex. Finally, a novel Golgi stacking model is proposed according to these structural findings. Structural Basis for the Interaction between Golgi Reassembly-stacking Protein GRASP55 and Golgin45.,Zhao J, Li B, Huang X, Morelli X, Shi N J Biol Chem. 2017 Feb 17;292(7):2956-2965. doi: 10.1074/jbc.M116.765990. Epub, 2017 Jan 3. PMID:28049725[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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