REGULATION OF ADENYLYL-CYCLASE FROM BLASTOCLADIELLA-EMERSONII BY GUANINE-NUCLEOTIDES

GTPgammaS stimulates adenylyl cyclase in particulate fractions of Blas tocladiella emersonii zoospores. Cholera toxin catalyses the ADP-ribos ylation of a membrane protein of a molecular weight (46,000) similar t o that of the a subunit of G(S) found in vertebrate cells. A membrane protein of 46 kDa can also be recognized in Western blots by an antipe ptide antiserum (RM/1) raised against the C-terminus of Galpha(S)-subu nits. These results suggest that a G-protein mediates the regulation o f Blastocladiella adenylyl cyclase by guanine nucleotides.