title: Phospholipase C-beta3 and -beta1 form homodimers, but not heterodimers, through catalytic and carboxyl-terminal domains.
abstract: 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.
authors.affiliation: Molecular and Cellular Biology Program, 203 Pharmacy Building, Oregon State University, Corvallis, OR 97331-3507, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Walter K
authors.initials: WK
authors.lastname: Vogel
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: McCullar
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Greenwood
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Filtz
mesh_terms: D000818:Animals; D020134:Catalytic Domain; D002478:Cells, Cultured; D002850:Chromatography, Gel; D019281:Dimerization; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D047468:Immunoprecipitation; D007527:Isoenzymes / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D054799:Phospholipase C beta; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D010738:Type C Phospholipases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D010738:Type C Phospholipases; C518033:PLCB1 protein, human; C518036:PLCB2 protein, human; C518039:PLCB3 protein, human; D054799:Phospholipase C beta; C518035:Plcb1 protein, rat; C518038:Plcb2 protein, rat; C518041:Plcb3 protein, rat