Phospholipase C-beta3 and -beta1 form homodimers, but not heterodimers, through catalytic and carboxyl-terminal domains.

Phospholipase C-beta (PLC-beta) isoenzymes are key effectors in G protein-coupled signaling pathways. Prior research suggests that some isoforms of PLC-beta may exist and function as dimers. Using coimmunoprecipitation assays of differentially tagged PLC-beta constructs and size-exclusion chromatography of native PLC-beta, we observed homodimerization of PLC-beta3 and PLC-beta1 isoenzymes but failed to detect heterodimerization of these isoenzymes. Size-exclusion chromatography data suggest that PLC-beta3 and PLC-beta1 form higher affinity homodimers than PLC-beta2. Evidence supportive of limited PLC-beta monomer-homodimer equilibrium appears at < or =100 nM. Further assessment of homodimerization status by coimmunoprecipitation assays with differentially tagged PLC-beta3 fragments demonstrated that at least two subdomains of PLC-beta3 are involved in dimer formation, one in the catalytic X and Y domains and the other in the G protein-regulated carboxyl-terminal domain. In addition, we provide evidence consistent with the existence of PLC-beta homodimers in a whole-cell context, using fluorescent protein-tagged constructs and microscopic fluorescence resonance energy transfer assays.

Citation

Yong Zhang, Walter K Vogel, Jennifer S McCullar, Jeffrey A Greenwood, Theresa M Filtz. Phospholipase C-beta3 and -beta1 form homodimers, but not heterodimers, through catalytic and carboxyl-terminal domains. Molecular pharmacology. 2006 Sep;70(3):860-8

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PMID: 16763092

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