Received for publication January 3, 2006.
Revised June 6, 2006.
Accepted for publication June 8, 2006.

Phospholipase C-3 And -1 Form Homodimers, But Not Heterodimers, Through Catalytic And Carboxy-Terminal Domains

Abstract

Phospholipase C- (PLC-) isoenzymes are key effectors in G protein-coupled signaling pathways. Prior research suggested that some isoforms of PLC- may exist and function as dimers. Using co-immunoprecipitation assays of differentially-tagged PLC- constructs and size-exclusion chromatography of native PLC-, we detected homodimerization of PLC-3 and PLC-1 isoenzymes, but failed to detect heterodimerization of these isoenzymes. Size-exclusion chromatography data suggest that PLC-3 and PLC-1 form higher affinity homodimers than PLC-2. Evidence supportive of limited PLC- monomer-homodimer equilibrium appears at 100 nM and lower. Further assessment of homodimerization status by co-immunoprecipitation assays with differentially-tagged PLC-3 fragments demonstrated that at least two subdomains of PLC-3 are involved in dimer formation, one in the catalytic X and Y domains, and the other in the G protein-regulated carboxy-terminal domain. Additionally, we provide evidence consisent with the existence of PLC- homodimers in a whole cell context, using fluorescent protein-tagged constructs and microscopic fluorescence resonance energy transfer assays.

Key words: Phospholipase C's, Fluorescence techniques

This article has been cited by other articles:

				C. Shao, X. Shi, H. Wehbi, C. Zambonelli, J. F. Head, B. A. Seaton, and M. F. Roberts Dimer Structure of an Interfacially Impaired Phosphatidylinositol-specific Phospholipase C J. Biol. Chem., March 23, 2007; 282(12): 9228 - 9235. [Abstract] [Full Text] [PDF]