4tu3
From Proteopedia
Crystal structure of yeast Sac1/Vps74 complex
Structural highlights
Function[SAC1_YEAST] Phosphoinositide phosphatase that hydrolyzes PtdIns(3)P and PtdIns(4)P. Has low activity towards PtdIns(3,5)P2. May be involved in the coordination of the activities of the secretory pathway and the actin cytoskeleton.[1] [2] [VPS74_YEAST] Phosphatidylinositol-4-phosphate-binding protein that links Golgi membranes to the cytoskeleton and may participate in the tensile force required for vesicle budding from the Golgi. Thereby, may play a role in Golgi membrane trafficking and could indirectly give its flattened shape to the Golgi apparatus. May also bind to the coatomer to regulate Golgi membrane trafficking. May play a role in anterograde transport from the Golgi to the plasma membrane and regulate secretion. Mediates the cis and medial Golgi localization of mannosyltransferases through direct binding of their cytosolic domains. Involved in vacuolar protein sorting.[3] [4] [5] Publication Abstract from PubMedSac1 is a phosphoinositide phosphatase of the endoplasmic reticulum and Golgi apparatus that controls organelle membrane composition principally via regulation of phosphatidylinositol 4-phosphate signaling. We present a characterization of the structure of the N-terminal portion of yeast Sac1, containing the conserved Sac1 homology domain, in complex with Vps74, a phosphatidylinositol 4-kinase effector and the orthologue of human GOLPH3. The interface involves the N-terminal subdomain of the Sac1 homology domain, within which mutations in the related Sac3/Fig4 phosphatase have been linked to Charcot-Marie-Tooth disorder CMT4J and amyotrophic lateral sclerosis. Disruption of the Sac1-Vps74 interface results in a broader distribution of phosphatidylinositol 4-phosphate within the Golgi apparatus and failure to maintain residence of a medial Golgi mannosyltransferase. The analysis prompts a revision of the membrane-docking mechanism for GOLPH3 family proteins and reveals how an effector of phosphoinositide signaling serves a dual function in signal termination. Sac1-Vps74 structure reveals a mechanism to terminate phosphoinositide signaling in the Golgi apparatus.,Cai Y, Deng Y, Horenkamp F, Reinisch KM, Burd CG J Cell Biol. 2014 Aug 18;206(4):485-91. doi: 10.1083/jcb.201404041. Epub 2014 Aug, 11. PMID:25113029[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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