1i9y
From Proteopedia
CRYSTAL STRUCTURE OF INOSITOL POLYPHOSPHATE 5-PHOSPHATASE DOMAIN (IPP5C) OF SPSYNAPTOJANIN
Structural highlights
Function[SYJ1_SCHPO] Controls the cellular levels and subcellular distribution of phosphatidylinositol 3-phosphate and phosphatidylinositol 4,5-bisphosphate. Involved in distinct membrane trafficking and signal transduction pathways. Highly active against a range of soluble and lipid inositol phosphates. Active in dephosphorylating the 5-position of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 and to a lesser extent Ins(1,4,5,6)P4. The enzyme is also active against PI(4,5)P2 presented in sonicated vesicles and Triton mixed micelles, and somewhat less active against PI(3,5)P2 in unilamellar vesicles. Activity against PI(3,5)P2 drops sharply when this substrate is presented in mixed micelles. Also hydrolyzes PIP3 to produce PI(3,4)P2.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedInositol polyphosphate 5-phosphatases are central to intracellular processes ranging from membrane trafficking to Ca(2+) signaling, and defects in this activity result in the human disease Lowe syndrome. The 1.8 resolution structure of the inositol polyphosphate 5-phosphatase domain of SPsynaptojanin bound to Ca(2+) and inositol (1,4)-bisphosphate reveals a fold and an active site His and Asp pair resembling those of several Mg(2+)-dependent nucleases. Additional loops mediate specific inositol polyphosphate contacts. The 4-phosphate of inositol (1,4)-bisphosphate is misoriented by 4.6 compared to the reactive geometry observed in the apurinic/apyrimidinic endonuclease 1, explaining the dephosphorylation site selectivity of the 5-phosphatases. Based on the structure, a series of mutants are described that exhibit altered substrate specificity providing general determinants for substrate recognition. Specificity determinants in phosphoinositide dephosphorylation: crystal structure of an archetypal inositol polyphosphate 5-phosphatase.,Tsujishita Y, Guo S, Stolz LE, York JD, Hurley JH Cell. 2001 May 4;105(3):379-89. PMID:11348594[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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