Discovered by Rodbell and co-workers at America’s NIH, and Oilman and co-workers at the American University of Virginia-Charlottesville, during the 1970s-80s. These are proteins embedded in the surface membrane of cells. G-proteins “receive chemical signals” from outside the cell (e.g., hormones) and “pass the signal” into the cell, so that cell can “respond to the signal.” For example, a hormone, drug, neurotransmitter, or other “signal” binds to a receptor molecule on the surface of the cell’s exterior membrane. That receptor then activates the G-protein, which causes an effector inside cell to produce a second “signal” chemical inside cell, which causes cell to react to the original external chemical signal. Dysfunction of G-proteins causes the salt and water losses inherent in cholera (the body’s compromised immune defense inherent in pertussis), and is believed responsible for some symptoms of diabetes and alcoholism.