Montserrat Camps (Molecular Pharmacology Division, German Cancer Research Center, Heidelberg, Germany): "This work was done in the laboratory of Peter Gierschik at the University of Heidelberg department of pharmacology. We were studying the regulation of phosphoinositide-specific phospholipases C (PI-PLCs) by signal-transducing heterotrimeric (a,bg) guanine nucleotide-binding proteins (G-proteins). G-proteins couple a large variety of cell-surface receptors to second messenger-generating effectors such as PI-PLC. In certain cells--for example, granulocytes--receptor-mediated stimulation of PI-PLC is blocked by pertussis toxin, while in other cells it is not. In 1990-91, PI-PLC was shown to be regulated by members of the aq subfamily of the G-protein a- subunits in pertussis toxin-resistant systems. In contrast, the pertussis toxin-sensitive pathway of PI-PLC stimulation
remained obscure until the publication of our work in 1992. "In this paper, we report that a PI-PLC present in cultured human HL-60 granulocytes is stimulated by G-protein bg- subunits, rather than by a-subunits. This finding ...
