Inositol polyphosphate multikinase regulates inositol 1,4,5,6-tetrakisphosphate.
Biochem Biophys Res Commun
; 339(1): 209-16, 2006 Jan 06.
Article
in En
| MEDLINE
| ID: mdl-16293229
ABSTRACT
The human inositol phosphate multikinase (IPMK, 5-kinase) has a preferred 5-kinase activity over 3-kinase and 6-kinase activities and a substrate preference for inositol 1,3,4,6-tetrakisphosphate (Ins(1,3,4,6)P4) over inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4). We now report that the recombinant human protein can catalyze the conversion of inositol 1,4,5,6-tetrakisphosphate (Ins(1,4,5,6)P4) to Ins(1,3,4,5,6)P5 in vitro; the reaction product was identified by HPLC to be Ins(1,3,4,5,6)P5. The apparent Vmax was 42 nmol of Ins(1,3,4,5,6)P5 formed/min/mg protein, and the apparent Km was 222 nM using Ins(1,3,4,6)P4 as a substrate; the catalytic efficiency was similar to that for Ins(1,4,5)P3. Stable over-expression of the human protein in HEK-293 cells abrogates the in vivo elevation of Ins(1,4,5,6)P4 from the Salmonella dublin SopB protein. Hence, the human 5-kinase may also regulate the level of Ins(1,4,5,6)P4 and have an effect on chloride channel regulation.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Phosphotransferases (Alcohol Group Acceptor)
/
Inositol Phosphates
Limits:
Humans
Language:
En
Journal:
Biochem Biophys Res Commun
Year:
2006
Document type:
Article
Affiliation country:
United States