The reference OMIM entry for this protein is 604114

Phospholipase c, beta-2; plcb2

DESCRIPTION

Phosphoinositide-specific phospholipase C (PLC) plays a major role in transmembrane signaling by catalyzing the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) and thereby generating the second messenger molecules inositol 1,4,5-trisphosphate (IP3) and diacylglycerol. Several distinct PLC enzymes have been identified in a variety of mammalian tissues (summary by Park et al., 1992). PLCB2 participates in the T2R (see 604791) signal transduction pathway (summary by Shah et al., 2009).

CLONING

Park et al. (1992) isolated cDNAs encoding a previously uncharacterized PLC by screening a human cDNA library derived from the promyelocytic cell line HL-60 with a bovine PLC-beta-1 (PLCB1) cDNA. The 1,181-amino acid protein predicted from the human cDNAs shares 48% amino acid identity with rat Plcb1 and is similar in overall structure to Plcb1; thus, it was named PLC-beta-2 (PLCB2). PLCB2 and Plcb1 show the least sequence similarity in their C-terminal 450 amino acids. PLCB2 contains the X and Y regions conserved among PLCs, and 1 PEST sequence, a motif suggesting sensitivity of PLCB2 to proteases. Recombinant PLCB2 expressed in mammalian cells migrated as a 140-kD protein in SDS-polyacrylamide gels. Characterization of recombinant PLCB2 revealed that the catalytic activity of PLCB2 is dependent on calcium and that PLCB2 prefers phosphatidylinositol 4,5-bisphosphate to phosphatidylinositol as a substrate. Reconstitution experiments showed that alpha-q (600998), which is the alpha subunit of the pertussis toxin-insensitive G protein, activates Plcb1 but not PLCB2, suggesting that receptor-dependent stimulation of these 2 PLCBs may require different G protein alpha subunits.

GENE FUNCTION

Santagata et al. (2001) demonstrated that tubby (601197) functions in signal transduction from heterotrimeric G protein-coupled receptors. Receptor-mediated activation of G-alpha-q releases tubby from the plasma membrane through the action of phospholipase C-beta, triggering translocation of tubby to the cell nucleus. The localization of tubby-like protein-3 (TULP3; 604730) is similarly regulated. Santagata et al. (2001) concluded that tubby proteins function as membrane-bound transcription regulators that translocate to the nucleus in response to phosphoinositide hydrolysis, providing a direct link between G protein signaling and the regulation of gene expression. Rao et al. (1989), Yang et al. (1996), Lee et al. (1996), and Mao et al. (2002) described a unique platelet function defect characterized by a deficiency in platelet PLCB2 isozyme. The proposita and her son had impaired platelet aggregation, serotonin secretion, mobilization of cytoplasmic ionized calcium, and PLC activation in response to several G protein-coupled receptor-mediated agonists, including adenosine diphosphate (ADP), thrombin (176930), platelet-activating factor (173393), and thromboxane A2 (188070). Platelet levels of PLCB2 were decreased to approximately one-third with normal levels of other PLC isozymes. In further studies, Mao et al. (2002) found that PLCB2 mRNA and protein levels were decreased in platelets but normal in the neutrophils from the patient, which suggested a lineage-specific defect in PLCB2 gene expression. Mao et al. (2002) found no mutation in the coding sequence (cDNA) of the PLCB2 gene. Shah et al. (2009) found that alpha-gustducin (139395) and PLCB2 are expressed in airway epithelia. Alpha-gustducin resides in the ... More on the omim web site

Subscribe to this protein entry history

Nov. 16, 2018: Protein entry updated
Automatic update: OMIM entry 604114 was added.

Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).