diphosphoinositol polyphosphate phosphohydrolase 2 (DIPP-2, diadenosine 5',5'-P1,P6-hexaphosphate hydrolase 2, nucleoside diphosphate-linked moiety X motif 4, nudix motif 4, NUDT4, DIPP2, HDCMB47P)

Function

• cleaves a beta-phosphate from the diphosphate groups in PP-InsP5, PP-InsP4 & [PP]2-InsP4 (bisdiphosphoinositol tetrakisphosphate), suggesting a role in signal transduction
• catalyzes hydrolysis of dinucleoside oligophosphate Ap6A, but not Ap5A; major reaction products are ADP & p4a from Ap6A
• hydrolyzes PRPP (5-phosphoribosyl 1-pyrophosphate)

diphospho-myo-inositol polyphosphate + H2O
                  <-->
myo-inositol polyphosphate + phosphate

Cofactor: Mg+2 or Mn+2

Kinetic parameters:

• KM=4.2 nM for PP-InsP5

Structure

• belongs to the Nudix hydrolase family, DIPP subfamily

Compartment

cytoplasm

Alternative splicing

named isoforms=3

Expression

e

• expressed in heart > skeletal muscle, pancreas, kidney

More general terms

• nucleoside diphosphate-linked moiety X motif

Database

• UniProt: http://www.uniprot.org/uniprot/Q9NZJ9.html