Difference between revisions of "Phosphatase Subfamily PPIP5K"
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=== Domain === | === Domain === | ||
| − | PPIP5K has two domains: N-terminal RimK/ATP-grasp domain, and C-terminal HP2 domain <cite>fridy07</cite>. The RimK is the active kinase domain <cite>fridy07, choi07</cite>. | + | PPIP5K has two domains: N-terminal RimK/ATP-grasp kinase domain, and C-terminal HP2 phosphatase domain <cite>fridy07</cite>. The RimK is the active kinase domain <cite>fridy07, choi07</cite>. |
Unlike other HP2 subfamilies 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 <cite>gokhale11</cite>. The HP2 domains of PPIP5Ks are longer than those of other HP2 subfamilies, due to the insertions at multiple sites. | Unlike other HP2 subfamilies 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 <cite>gokhale11</cite>. The HP2 domains of PPIP5Ks are longer than those of other HP2 subfamilies, due to the insertions at multiple sites. | ||
Revision as of 18:03, 12 April 2017
Phosphatase Classification: Fold HP: Superfamily HP: Family HP, branch 2 (HP2): Subfamily PPIP5K
PPIP5K is a phosphoinositol kinase that also has a pseudophosphatase domain which binds to PtdIns(3,4,5)P3. PPIP5K converts InsP6 and 5-InsP7 to 1-InsP7 and InsP8.
Evolution
PPIP5K is found in most eukaryotes, but is missing in alveolates. Most vertebrates have at least two copies, while invertebrates usually have one.
Domain
PPIP5K has two domains: N-terminal RimK/ATP-grasp kinase domain, and C-terminal HP2 phosphatase domain [1]. The RimK is the active kinase domain [1, 2].
Unlike other HP2 subfamilies 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]. The HP2 domains of PPIP5Ks are longer than those of other HP2 subfamilies, due to the insertions at multiple sites.
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 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 |
