View source for Kinase Subfamily IP3K

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[[kinase classification|Kinase Classification]]: [[Kinase_Group_PKL|Group PKL]]:  [[Kinase_Family_IPK|Subfamily IPK]]: [[Kinase_Subfamily_IP3K|Subfamily IP3K]]

IP3K is a non-protein kinase that phosphorylates inositol (1,4,5) tri-phosphate on the 3 position, to create Ins(1,3,4,5)P4.

====Kinase Domain====
The IPPK kinase domain is most similar to that of [[Kinase_Family_PIPK|PIPK]], which is itself a remote member of the PKL fold, and related to other inositol phosphate kinase families <cite>Gonzalez, Miller</cite>. SCOP classifies both IP3K (called IPK) and PIPK in the [http://scop.berkeley.edu/sunid=56104 SAICAR synthase-like superfamamily] with similarity to both the PKL and the ATP-Grasp folds. This was first predicted by deep sequence comparison <cite>Cheek</cite> and confirmed by a crystal structures <cite>Miller, Takazawa, Gonzalez</cite>. Like [[Kinase_Family_PIPK|PIPK]] kinases, the N-lobe is closer to PKL while the C-lobe has similarities to the ATP-Grasp fold. The [[K72]], [[D166]] and [[D184]] catalytic residues of PKLs are well conserved in IP3K <cite>Cheek</cite>.

====Evolution====
The family is found in most eukaryotes, and has three copies in human (ITPKA, ITPKB, ITPKC).

====Naming====
As with most inositol kinases, IP3K have several names, I3P3K, IP3-3K, ITPK (inositol-trisphosphate 3-kinase) and 1D-myo-inositol 1,4,5-trisphosphate 3-kinase. While human names are named with the root ITPK, this is also the name of a different family of lipid kinases.

====References====
<biblio>
#Gonzalez pmid=15350214
#Miller pmid=15350215
#Takazawa pmid=1847047
#Cheek pmid=15771780
</biblio>