GPCR (1 of 3) (IMAGE) DOE/SLAC National Accelerator Laboratory Caption This illustration shows a man suffering from a migraine, overlain with a rendering of the human serotonin receptor bound to ergotamine, an anti-migraine drug. Also shown is a rendering of a neuron network. Scientists used SLAC's Linac Coherent Light Source X-ray laser to explore crystallized samples of the serotonin receptor, which is a type of G protein-coupled receptor. GPCRs regulate many important functions in human physiology; serotonin, for example, is a neurotransmitter that regulates mood, appetite and sleep. Credit Katya Kadyshevskaya/The Scripps Research Institute Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.