A cDNA encoding G16α, the α subunit of a heterotrimeric guanine nucleotide-binding protein, was expressed in Sf9 cells using recombinant baculovirus. G16α in membrane extracts of Sf9 cells activated phospholipase C-β1 (PLC-β1) in the presence of guanosine 5′-[γ-thio]triphosphate; the system could not be activated by Al3+, Mg2+, and F-. The G16α in the cytosolic fraction of Sf9 cells did not stimulate PLC-β1. Concurrent expression of the G-protein βγ subunit complex increased the amount of G16α in Sf9 cell membranes. The guanosine 5′-[γ-thio]triphosphate-activated form of G16α was purified from cholate extracts of membranes from cells expressing G16α, and the G-protein β2 and γ2 subunits. G16α activated PLC-β1, PLC-β2, and PLC-β3 in a manner essentially indistinguishable from that of Gqα. G16α-mediated activation of PLC-β1 and PLC-β3 greatly exceeded that of PLC-β2. G16α did not activate PLC-γ1 or PLC-δ. Thus, two distantly related members of the Gqα family, Gqα and G16α, have the same ability to activate the known isoforms of PLC-β.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Oct 1 1993|
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