G beta association and effector interaction selectivities of the divergent G gamma subunit G gamma(13).
G gamma(13) is a divergent member of the G gamma subunit family considered to be a component of the gustducin G-protein heterotrimer involved in bitter and sweet taste reception in taste bud cells. G gamma(13) contains a C-terminal asparagine-proline-tryptophan (NPW) tripeptide, a hallmark of RGS protein G gamma-like (GGL) domains ... which dimerize exclusively with G beta(5) subunits. In this study, we investigated the functional range of G gamma(13) assembly with G beta subunits using multiple assays of G beta association and G beta gamma effector modulation. G gamma(13) was observed to associate with all five G beta subunits (G beta(1-5)) upon co-translation in vitro, as well as function with all five G beta subunits in the modulation of Kir3.1/3.4 (GIRK1/4) potassium and N-type (alpha(1B)) calcium channels. Multiple G beta/G gamma(13) pairings were also functional in cellular assays of phospholipase C (PLC) beta 2 activation and inhibition of G alpha(q)-stimulated PLC beta 1 activity. However, upon cellular co-expression of G gamma(13) with different G beta subunits, only G beta(1)/G gamma(13), G beta(3)/G gamma(13), and G beta(4)/G gamma(13) pairings were found to form stable dimers detectable by co-immunoprecipitation under high-detergent cell lysis conditions. Collectively, these data indicate that G gamma(13) forms functional G beta gamma dimers with a range of G beta subunits. Coupled with our detection of G gamma(13) mRNA in mouse and human brain and retina, these results imply that this divergent G gamma subunit can act in signal transduction pathways other than that dedicated to taste reception in sensory lingual tissue.
Mesh Terms:
Amino Acid Sequence, Animals, Calcium Channels, N-Type, Cell Line, Dimerization, Enzyme Activation, Green Fluorescent Proteins, Heterotrimeric GTP-Binding Proteins, Humans, Indicators and Reagents, Isoenzymes, Luminescent Proteins, Molecular Sequence Data, Patch-Clamp Techniques, Phospholipase C beta, Potassium Channels, Protein Isoforms, Protein Subunits, Sequence Alignment, Tissue Distribution, Type C Phospholipases
Amino Acid Sequence, Animals, Calcium Channels, N-Type, Cell Line, Dimerization, Enzyme Activation, Green Fluorescent Proteins, Heterotrimeric GTP-Binding Proteins, Humans, Indicators and Reagents, Isoenzymes, Luminescent Proteins, Molecular Sequence Data, Patch-Clamp Techniques, Phospholipase C beta, Potassium Channels, Protein Isoforms, Protein Subunits, Sequence Alignment, Tissue Distribution, Type C Phospholipases
J. Biol. Chem.
Date: Dec. 28, 2001
PubMed ID: 11675383
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