Goodman shared the 1994 Nobel Prize in Physiology or Medicine with Martin Rodbell "for their discovery of G-proteins and the role of these proteins in signal transduction in cells." In this paper Goodman and Ross showed that a guanine nucleotide binding protein (a "G" protein) activates adenylate cyclase. They posited a system whereby a hormone receptor (adrenergic), interacts with guanine nucleotides (G proteins), and these in turn activate the enzyme adenylate cyclase, but they qualified this with a statement that "proof of function of each entity must await their purification."
Digital facsimile from PubMedCentral at this link.
(Thanks to Juan Weiss for this reference and its interpretation.)