1w2c

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spinqualitylabelsall models PDB ID 1w2c Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
, resolution 1.95Å
Sites:
Ligands:	, , and
Activity:	Transferase, with EC number 2.1.7.127
Coordinates:	save as pdb, mmCIF, xml

HUMAN INOSITOL (1,4,5) TRISPHOSPHATE 3-KINASE COMPLEXED WITH MN2+/AMPPNP/INS(1,4,5)P3

Overview

Mammalian cells produce a variety of inositol phosphates (InsPs), including Ins(1,4,5)P3 that serves both as a second messenger and as a substrate for inositol polyphosphate kinases (IPKs), which further phosphorylate it. We report the structure of an IPK, the human Ins(1,4,5)P3 3-kinase-A, both free and in complexes with substrates and products. This enzyme catalyzes transfer of a phosphate from ATP to the 3-OH of Ins(1,4,5)P3, and its X-ray crystal structure provides a template for understanding a broad family of InsP kinases. The catalytic domain consists of three lobes. The N and C lobes bind ATP and resemble protein and lipid kinases, despite insignificant sequence similarity. The third lobe binds inositol phosphate and is a unique four-helix insertion in the C lobe. This lobe embraces all of the phosphates of Ins(1,4,5)P3 in a positively charged pocket, explaining the enzyme's substrate specificity and its inability to phosphorylate PtdIns(4,5)P2, the membrane-resident analog of Ins(1,4,5)P3.

About this Structure

1W2C is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Structure of a human inositol 1,4,5-trisphosphate 3-kinase: substrate binding reveals why it is not a phosphoinositide 3-kinase., Gonzalez B, Schell MJ, Letcher AJ, Veprintsev DB, Irvine RF, Williams RL, Mol Cell. 2004 Sep 10;15(5):689-701. PMID:15350214

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