GUANINE NUCLEOTIDE BINDING PROTEINS AS RECEPTOR-EFFECTOR COUPLERS

A family of guanine nucleotide binding proteins (G-proteins)
functions in transmembrane signalling as receptor-effector
couplers. G proteins couple to a diverse array of receptors
including those for hormones, neurotransmitters, light, odorants,
and certain growth factors. Effector functions regulated
(positively and, in some instances, negatively) by G-proteins
include cAMP formation, phosphoinositide breakdown, potassium
an calcium channels, and cGMP degradation. We have used a
variety of techniques to study the expression, distribution,
regulation, structure and function of G-proteins. Our studies
highlight the diversity within the G-protein family. We have
purified novel G-proteins and using cloned cDNAs, defined their
primary structure and distribution. We have demonstrated
developmental and differentiation-dependent regulation of G
protein synthesis. Using peptide specific antibodies, in situ
hybridization and northern analyses, and protein reconstitution
techniques, we have defined the specificity of G-proteins in
coupling to receptors and effectors. These studies provide the
basis for understanding the role of G-proteins in normal signal
transduction and for elucidating possible defects in G-protein
structure or function as the basis for abnormal signal
transduction.