diphosphoinositol polyphosphate phosphohydrolase 1 (DIPP-1, diadenosine 5',5'-P1,P6-hexaphosphate hydrolase 1, nucleoside diphosphate-linked moiety X motif 3, Nudix motif 3, NUDT3, DIPP, DIPP1)

Function

• cleaves beta-phosphate from diphosphate groups in IP5 & IP4
• role in signal transduction
• IP6 is not a substrate
• acts as negative regulator of the ERK1/2 pathway
• catalyzes hydrolysis of dinucleoside oligophosphates, with Ap6A & Ap5A as preferred substrates
• major reaction products are ADP & p4a from Ap6A & ADP & ATP from Ap5A
• hydrolyzes PRPP

diphospho-myo-inositol polyphosphate + H2O

<-->

myo-inositol polyphosphate + phosphate

Cofactor: Mg+2

Inhibition:

• inhibited by fluoride & InsP6

Kinetic parameters:

• KM=5.9 uM for Ap6A
• KM=7.7 uM for Ap5A
• KM=38 mM for PRPP
• KM=4.2 nM for PP-InsP5
• Optimum pH is 7-7.5

Structure

• monomer
• belongs to the Nudix hydrolase family. DIPP subfamily

Compartment

cytoplasm

Expression

• widely expressed
• expressed at higher level in brain, heart, pancreas, liver
• also expressed in placenta, lung, kidney

More general terms

• phosphomonoesterase
• nucleoside diphosphate-linked moiety X motif

Database

• UniProt: http://www.uniprot.org/uniprot/O95989.html