1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase delta-3 (phosphoinositide phospholipase C delta-3, PLC-delta-3, phospholipase C-delta-3, PLCD3, KIAA1964)

Function

• hydrolyzes the phosphatidylinositol 4,5-bisphosphate (PIP2) to generate 2 second messenger molecules diacylglycerol (DAG) & inositol 1,4,5-trisphosphate (IP3)
• essential for trophoblast & placental development
• may participate in cytokinesis by hydrolyzing PIP2 at the cleavage furrow
• strongly activated by phosphatidic acid
• inhibited by phosphatidylethanolamine (PtdEtn), phosphatidylcholine (PtdCho), sphingomyelin & phosphatidylserine (PtdSer)

Kinetic parameters:

• KM=105.3 uM for PIP2
• Vmax=28.5 umol/min/mg enzyme

1-phosphatidyl-1D-myo-inositol 4,5- bisphosphate + H2O

<-->

1D-myo-inositol 1,4,5-trisphosphate + diacylglycerol

Cofactor:

• binds 3 Ca+2 per subunit
• to=wo Ca+2 are bound to the C2 domain (probable)

Structure

• C2 domain is a Ca+2-dependent membrane-targeting module
• PH domain mediates interaction with surface membrane by binding to PIP2
• contains 1 C2 domain
• contains 3 EF-hand domains
• contains 1 PH domain
• contains 1 PI-PLC X-box domain
• contains 1 PI-PLC Y-box domain

Compartment

• membrane, peripheral membrane, cytoplasm
• localizes at the cleavage furrow during cytokinesis

Expression

• present in corneal epithelial cells (at protein level)
• down-regulated by Ca+2 & cAMP

More general terms

• phosphoprotein
• phosphodiesterase
• Ca+2 binding protein

Database

• OMIM: https://mirror.omim.org/entry/608795
• UniProt: http://www.uniprot.org/uniprot/Q8N3E9.html