Transmembrane signalling to adenylate cyclase in mammalian cells and in Saccharomyces cerevisiae

An increasing number of transmembrane signalling systems are being found to transduce signals through heterotrimeric guanyl nucleotide binding proteins (G proteins). One of the most intensively studied systems is that of adenylate cyclase, in which two distinct G protein transducing systems that respond to stimulatory and inhibitory receptors, respectively, have been identified. The identification of a RAS protein which is a monomeric G protein as a transducer element in the activation of adenylate cyclase in the yeast S. cerevisiae opens new avenues towards understanding the function of ras protein in mammalian cells.