[Signal transfer from beta-adrenergic receptor to adenylate cyclase (author's transl)].

Hormonally stimulated adenylate cyclase of vertebrate cells is composed of at least three components which span the bilayer of the biological membrane: a hormone receptor, a GTP-binding coupling unit and a catalytic component synthesizing cAMP from ATP. The coupling unit possesses GTPase activity enabling the hormonal signal to be delicately regulated. The molecular mechanism by which the enterotoxin of Vibrio cholerae exerts its action, is an ADP-ribosyl transfer to the GTP-binding component, which causes the inhibition of the GTPase. As a consequence excessive cAMP is synthesized followed by a massive loss of water and electrolytes from the cell.