%0 Journal Article %A Yong Zhang %A Walter K. Vogel %A Jennifer S. McCullar %A Jeffrey A. Greenwood %A Theresa M. Filtz %T Phospholipase C-β3 and -β1 Form Homodimers, but Not Heterodimers, through Catalytic and Carboxyl-Terminal Domains %D 2006 %R 10.1124/mol.105.021923 %J Molecular Pharmacology %P 860-868 %V 70 %N 3 %X Phospholipase C-β (PLC-β) isoenzymes are key effectors in G protein-coupled signaling pathways. Prior research suggests that some isoforms of PLC-β may exist and function as dimers. Using coimmunoprecipitation assays of differentially tagged PLC-β constructs and size-exclusion chromatography of native PLC-β, we observed homodimerization of PLC-β3 and PLC-β1 isoenzymes but failed to detect heterodimerization of these isoenzymes. Size-exclusion chromatography data suggest that PLC-β3 and PLC-β1 form higher affinity homodimers than PLC-β2. Evidence supportive of limited PLC-β monomer-homodimer equilibrium appears at ≤100 nM. Further assessment of homodimerization status by coimmunoprecipitation assays with differentially tagged PLC-β3 fragments demonstrated that at least two subdomains of PLC-β3 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-β homodimers in a whole-cell context, using fluorescent protein-tagged constructs and microscopic fluorescence resonance energy transfer assays. The American Society for Pharmacology and Experimental Therapeutics %U https://molpharm.aspetjournals.org/content/molpharm/70/3/860.full.pdf