Difference between revisions of "Phosphatase Subfamily PPIP5K"
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=== Catalytic activity and functions === | === Catalytic activity and functions === | ||
| + | The phosphatase domains of human PPIP5K1 and PPIP5K2 are catalytically inactive, though they bear the histidine residue at catalytic core (figure 5 in <cite>rigden08</cite>). It is unclear whether PPIP5K are conservatively inactive in other genomes. | ||
=== References === | === References === | ||
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#choi07 pmid=17702752 | #choi07 pmid=17702752 | ||
#gokhale11 pmid=21222653 | #gokhale11 pmid=21222653 | ||
| + | #rigden08 pmid=18092946 | ||
</biblio> | </biblio> | ||
Revision as of 18:28, 8 January 2015
Phosphatase Classification: Fold HP: Superfamily HP (histidine phosphatase): Family HP, branch 2: PPIP5K
PPIP5K is a phosphoinositol kinase that also has a pseudophosphatase domain which bind to PtdIns(3,4,5)P3. PPIP5K converts InsP6 and 5-InsP7 to 1-InsP7 and InsP8.
Evolution
PPIP5K is found in most eukaryotes. Most vertebrates have at least two copies, while invertebrates usually have one.
Domain
PPIP5K has two domains: N-terminal RimK/ATP-grasp domain, and C-terminal HP2 domain [1]. The RimK is the active kinase domain [1, 2].
Unlike other members of HP2 family which are protein or non-protein phosphatases, the HP2 domain of PPIP5K is not catalytically active. Instead, this HP2 domain is specialized for binding PtdIns(3,4,5)P3, as a partial PH (pleckstrin homology) consensus sequence is spliced into this HP2 domain [3].
Catalytic activity and functions
The phosphatase domains of human PPIP5K1 and PPIP5K2 are catalytically inactive, though they bear the histidine residue at catalytic core (figure 5 in [4]). It is unclear whether PPIP5K are conservatively inactive in other genomes.
References
- Fridy PC, Otto JC, Dollins DE, and York JD. Cloning and characterization of two human VIP1-like inositol hexakisphosphate and diphosphoinositol pentakisphosphate kinases. J Biol Chem. 2007 Oct 19;282(42):30754-62. DOI:10.1074/jbc.M704656200 |
- Choi JH, Williams J, Cho J, Falck JR, and Shears SB. Purification, sequencing, and molecular identification of a mammalian PP-InsP5 kinase that is activated when cells are exposed to hyperosmotic stress. J Biol Chem. 2007 Oct 19;282(42):30763-75. DOI:10.1074/jbc.M704655200 |
- Gokhale NA, Zaremba A, and Shears SB. Receptor-dependent compartmentalization of PPIP5K1, a kinase with a cryptic polyphosphoinositide binding domain. Biochem J. 2011 Mar 15;434(3):415-26. DOI:10.1042/BJ20101437 |
- Rigden DJ. The histidine phosphatase superfamily: structure and function. Biochem J. 2008 Jan 15;409(2):333-48. DOI:10.1042/BJ20071097 |
