nucleoside diphosphate-linked moiety X motif 11 (diphosphoinositol polyphosphate phosphohydrolase 3 beta, DIPP-3 beta, DIPP3 beta, hDIPP3beta, diadenosine 5',5'-P1,P6-hexaphosphate hydrolase 3 beta, hAps1, Nudix motif 11, NUDT11, APS1, DIPP3B)

Function

• cleaves a beta-phosphate from the diphosphate groups in PP-InsP5 (diphosphoinositol pentakisphosphate), suggesting that it may play a role in signal transduction
• catalyzes hydrolysis of dinucleoside oligophosphates, with Ap6A & Ap5A as preferred substrates
  • major reaction products are ADP & p4a from Ap6A & ADP & ATP from Ap5A
• able to hydrolyze PRPP (5-phosphoribosyl 1-pyrophosphate)

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

Cofactor: Mg+2, Mn+2, Mn+2 may be true cofactor in vivo

Kinetic parameters:

• KM=0.053 uM for PP-InsP5
• KM=13 uM for Ap6A
• KM=37 uM for Ap5A
• Optimum pH is 8.5

Structure

belongs to the Nudix hydrolase family, DIPP subfamily

Compartment

cytoplasm

Expression

• mainly expressed in testis, at lower level in brain
• also expressed in pancreas & weakly expressed in thymus, prostate, ovary, lung, small intestine & heart

More general terms

• nucleoside diphosphate-linked moiety X motif
• phosphoprotein

Database

• UniProt: http://www.uniprot.org/uniprot/Q96G61.html