Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosducin-like protein is a protein with wide-spread expression that has been shown to be capable of inhibiting G-protein function in vitro. However, it is not clear whether it is expressed in sufficient amounts to actually exert such functions in vivo. Here we quantify the expression of the short and the long splice variants of phosducin-like protein, PhlPs and PhlP1. Western blots of various rat tissues showed that PhlP1 was by far the dominant splice variant; its levels were 1.5-2 pmol/mg cytosolic protein in brain, liver and kidney, and about 0.5 pmol/mg cytosolic protein in lung, heart and skeletal muscle. These values correspond to concentrations of 150-200 nM and 50 nM, respectively. The levels of PhlPs were about 20-fold lower. Recombinant phosducin, PhlP1 and PhlPs inhibited the interaction between G-protein alpha- und betagamma-subunits with IC50-values of 6 nM, 6 nM and 90 nM, respectively, as determined by Gbetagamma-dependent ADP-ribosylation of Galphai1 by pertussis-toxin. Thus, tissue concentrations of PhlP1 are clearly sufficient to affect G-protein function in vivo, while the expression levels and the Gbetagamma-affinity of PhlPs are most likely too low to have significant inhibitory effects on Gbetagamma (G-protein betagamma-subunits).
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PMID:Quantification of the tissue levels and function of the G-protein regulator phosducin-like protein (PhlP). 1111 39

Phosducin-like protein (PhLP) is a broadly expressed member of the phosducin (Pd) family of G protein betagamma subunit (Gbetagamma)-binding proteins. Though PhLP has been shown to bind Gbetagamma in vitro, little is known about its physiological function. In the present study, the effect of PhLP on angiotensin II (Ang II) signaling was measured in Chinese hamster ovary cells expressing the type 1 Ang II receptor and various amounts of PhLP. Up to 3.6-fold overexpression of PhLP had no effect on Ang II-stimulated inositol trisphosphate (IP(3)) formation, whereas further increases caused an abrupt decrease in IP(3) production with half-maximal inhibition occurring at 6-fold PhLP overexpression. This threshold level for inhibition corresponds to the cellular concentration of cytosolic chaperonin complex, a recently described binding partner that preferentially binds PhLP over Gbetagamma. Results of pertussis toxin sensitivity, GTPgammaS binding, and immunoprecipitation experiments suggest that PhLP inhibits phospholipase Cbeta activation by dual mechanisms: (i) steric blockage of Gbetagamma activation of PLCbeta and (ii) interference with Gbetagamma-dependent cycling of G(q)alpha by the receptor. These results suggest that G protein signaling may be regulated through controlling the cellular concentration of free PhLP by inducing its expression or by regulating its binding to the chaperonin.
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PMID:Regulation of angiotensin II-induced G protein signaling by phosducin-like protein. 1210 86