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 is a cytosolic protein predominantly expressed in the retina and the pineal gland that can interact with the betagamma subunits of guanine nucleotide binding proteins (G proteins) and thereby may regulate transmembrane signaling. A cDNA encoding a phosducin-like protein (PhLP) has recently been isolated from rat brain [Miles, M. F., Barhite, S., Sganga, M. & Elliott, M. (1993) Proc. Natl. Acad. Sci. USA 90, 10831-10835. Here we report the expression of PhLP in Escherichia coli and its purification. Recombinant purified PUP inhibited multiple effects of G-protein betagamma subunits. First, it inhibited the betagamma-subunit-dependent ADP-ribosylation of purified alpha(o) by pertussis toxin. Second, it inhibited the GTPase activity of purified G(o). The IC50 value of PhLP in the latter assay was 89 nM, whereas phosducin caused half-maximal inhibition at 17 nM. And finally, PhLP antagonized the enhancement of rhodopsin phosphorylation by purified betagamma subunits. The N terminus of PhLP shows no similarity to the much longer N terminus of phosducin, the region shown to be critical for phosducin-betagamma-subunit interactions. Therefore, PhLP appears to bind to G-protein betagamma subunits by an as yet unknown mode of interaction and may represent an endogenous regulator of G-protein function.
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PMID:Inhibition of G-protein betagamma-subunit functions by phosducin-like protein. 870 Aug 91

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