inositol-tetrakisphosphate 1-kinase; inositol-1,3,4-trisphosphate 5/6-kinase; inositol-triphosphate 5/6-kinase; ins(1,3,4)P(3) 5/6-kinase (ITPK1)

Function

• phosphorylates Ins(1,3,4)P3 & Ins(3,4,5,6)P4
• phosphorylates Ins(3,4,5,6)P4 at position 1 to form Ins(1,3,4,5,6)P5.
• phosphorylates Ins(1,3,4)P3 on O-5 and O-6 to form Ins(1,3,4,5,6)P5
• dephosphorylates Ins(1,3,4,5)P4 & Ins(1,3,4,6)P4 to Ins(1,3,4)P3, & Ins(1,3,4,5,6)P5 to Ins(3,4,5,6)P4
• interconverts the inositol tetraphosphateisomers Ins(1,3,4,5)P4 & Ins(1,3,4,6)P4
• rate-limiting enzyme of the InsP6 pathway
• modifies TNF-alpha-induced apoptosis by interfering with the activation of TNFRSF1A-associated death domain

Cofactor: binds 2 Mg+2 ions.

Structure

• belongs to the ITPK1 family
• contains 1 ATP-grasp domain

Alternative splicing

named isoforms=2

Expression

• expressed in brain > heart > skeletal muscle = liver > lung
• in brain, expressed in cerebellum, cerebral cortex, medulla, spinal cord, occipital lobe, frontal lobe, temporal lobe & putamen

More general terms

• kinase or ATP-phosphotransferase

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=3705
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:3705
• OMIM: https://mirror.omim.org/entry/601838
• UniProt: http://www.uniprot.org/uniprot/Q13572.html