1z2o
Inositol 1,3,4-trisphosphate 5/6-Kinase in complex with mg2+/ADP/Ins(1,3,4,6)P4
OverviewOverview
Inositol hexakisphosphate and other inositol high polyphosphates have diverse and critical roles in eukaryotic regulatory pathways. Inositol 1,3,4-trisphosphate 5/6-kinase catalyzes the rate-limiting step in inositol high polyphosphate synthesis in animals. This multifunctional enzyme also has inositol 3,4,5,6-tetrakisphosphate 1-kinase and other activities. The structure of an archetypal family member, from Entamoeba histolytica, has been determined to 1.2 A resolution in binary and ternary complexes with nucleotide, substrate, and product. The structure reveals an ATP-grasp fold. The inositol ring faces ATP edge-on such that the 5- and 6-hydroxyl groups are nearly equidistant from the ATP gamma-phosphate in catalytically productive phosphoacceptor positions and explains the unusual dual site specificity of this kinase. Inositol tris- and tetrakisphosphates interact via three phosphate binding subsites and one solvent-exposed site that could in principle be occupied by 18 different substrates, explaining the mechanisms for the multiple specificities and catalytic activities of this enzyme.
About this StructureAbout this Structure
1Z2O is a Single protein structure of sequence from Eukaryota. Full crystallographic information is available from OCA.
ReferenceReference
Specificity determinants in inositol polyphosphate synthesis: crystal structure of inositol 1,3,4-trisphosphate 5/6-kinase., Miller GJ, Wilson MP, Majerus PW, Hurley JH, Mol Cell. 2005 Apr 15;18(2):201-12. PMID:15837423 Page seeded by OCA on Sat May 3 17:06:48 2008