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PLCβ enzymes

Activity

Phospholipase C beta (PLCβ) enzymes cleave PIP2 to produce inositol triphosphate (IP3) and diacylglycerol (DAG). IP3 activates the IP3 receptor on the ER leading to Ca2+ release into the cytoplasm and DAG activates protein kinase C (PKC), leading to additional downstream effects. Depletion of PIP2 from the plasma membrane also regulates the function of many membrane proteins, including ion channels and transporters. DAG also alters the properties of the membrane, including thickness and rigidity, regulating additional targets. Therefore, PLCβ activity mediates a multifaceted cellular response and must be tightly regulated.

Regulation

PLCβ enzymes are regulated by GPCR signaling, through Gαi and Gαq-coupeld pathways. As shown below, our previous work demonstrated that Gβγ subunits activate PLCβ enzymes by increasing their local concentration at the membrane and Gαq subunits activate PLCβ by increasing the catlaytic rate constant, kcat. PLCβ enzymes are also regulated by numerous cellular factors including small GTPases and lipids, which we are working to understand.

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