text: G proteins were discovered in 1980 when Alfred G. Gilman and Martin Rodbell investigated stimulation of cells by adrenaline. They found that when adrenaline binds to a receptor, the receptor does not stimulate enzymes (inside the cell) directly. Instead, the receptor stimulates a G protein, which then stimulates an enzyme. An example is adenylate cyclase, which produces the second messenger cyclic AMP. For this discovery, they won the 1994 Nobel Prize in Physiology or Medicine.
  Nobel prizes have been awarded for many aspects of signaling by G proteins and GPCRs. These include receptor antagonists, neurotransmitters, neurotransmitter reuptake, G protein-coupled receptors, G proteins, second messengers, the enzymes that trigger protein phosphorylation in response to cAMP, and consequent metabolic processes such as glycogenolysis.
  Prominent examples include (in chronological order of awarding):
  * The 1947 Nobel Prize in Physiology or Medicine to Carl Cori, Gerty Cori and Bernardo Houssay, for their discovery of how glycogen is broken down to glucose and resynthesized in the body, for use as a store and source of energy. Glycogenolysis is stimulated by numerous hormones and neurotransmitters including adrenaline.
  * The 1970 Nobel Prize in Physiology or Medicine to Julius Axelrod, Bernard Katz and Ulf von Euler for their work on the release and reuptake of neurotransmitters.
  * The 1971 Nobel Prize in Physiology or Medicine to Earl Sutherland for discovering the key role of adenylate cyclase, which produces the second messenger cyclic AMP.
  * The 1988 Nobel Prize in Physiology or Medicine to George H. Hitchings, Sir James Black and Gertrude Elion "for their discoveries of important principles for drug treatment" targeting GPCRs.
  * The 1992 Nobel Prize in Physiology or Medicine to Edwin G. Krebs and Edmond H. Fischer for describing how reversible phosphorylation works as a switch to activate proteins, and to regulate various cellular processes including glycogenolysis.
  * The 1994 Nobel Prize in Physiology or Medicine to Alfred G. Gilman and Martin Rodbell for their discovery of "G-proteins and the role of these proteins in signal transduction in cells".
  * The 2000 Nobel Prize in Physiology or Medicine to Eric Kandel, Arvid Carlsson and Paul Greengard, for research on neurotransmitters such as dopamine, which act via GPCRs.
  * The 2004 Nobel Prize in Physiology or Medicine to Richard Axel and Linda B. Buck for their work on G protein-coupled olfactory receptors.
  * The 2012 Nobel Prize in Chemistry to Brian Kobilka and Robert Lefkowitz for their work on GPCR function.