View source for Kinase Family ITPK

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[[kinase classification|Kinase Classification]]: [[Kinase_Group_PKL|Group PKL]]: [[Kinase_Family_ITPK|Family ITPK]]

ITPK in an inositol lipid kinase, once thought to have protein kinase activity. ITPK is an Inositol 1, 3, 4-trisphosphate 5/6-kinase.

====Kinase Domain====
ITPK has an ATP-grasp domain, shared by a variety of ATP-hydrolyzing metabolic enzymes. The [[Kinase_Family_PIPK|PIPK]] family of phosphatidyl inositol phosphate kinases is weakly related, in having a kinase domain that is related both to ATP-grasp and [[PKL]] kinases, so we classify this among the larger set of PKL kinases.

====Claimed Protein Kinase Activity====
Two reports showed protein kinase activity associated with human IPTK1 <cite>Sun, Wilson</cite>, when moderately purified from human cell culture. The kinase activity could phosphorylate several transcription factors and copurified with the COP9 signalosome complex. However, a later study <cite>Qian</cite> separated the protein and lipid kinase activities chromatographically, indicating that the original report may have been due to a contaminating protein kinase. Several predicted kinase-dead mutations abolished lipid kinase activity but did not affect the associated protein kinase activity.

====Naming====
The single human member is called ITPK1, but should not be confused with the human genes ITPKA, ITPKB and ITPKC, which belong to the IP3K family.

====References====
<biblio>
#Qian pmid=15762844
#Sun pmid=12324474
#Wilson pmid=11533064
</biblio>