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Nobel in Chemistry reveals VU ties that bind

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Three-dimensional structure of a G protein-coupled receptor or GPCR (magenta) embedded in a cell membrane, with its loosely attached G protein, consisting of three subunits: alpha (blue), beta (dark green) and gamma (gold). When a neurotransmitter, hormone or other ligand (bright yellow, at top) binds to its GPCR, the receptor changes shape in a way that catalyzes the release of guanosine diphosphate or GDP (red) from the alpha subunit. GDP, an organic molecule involved in intracellular energy exchange, is replaced by the higher energy guanosine triphosphate or GTP (bright green). That, in turn, causes the alpha subunit to break apart from the beta and gamma subunits. The subunits then interact with other intracellular proteins to transmit signals down two independent pathways. Within a few seconds, GTP is converted back to GDP, the subunits recombine, and the signals are “turned off.” (Illustration by William Oldham; courtesy of Heidi Hamm)

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