The Glycine Receptor of Rat Spinal Cord: Exploring the Site of Action of the Plant Alkaloid Strychnine

Abstract The amino acid glycine is a major neurotransmitter in the spinal cord of all vertebrates and is involved in the control of various motor and sensory functions. By binding to specific receptors of the neuronal plasma membrane, glycine produces an increase in chloride permeability and thus a hyperpolarization, i.e., an inhibition of glycine‐sensitive neurons. This inhibitory action of glycine is reversibly blocked by the plant alkaloid strychnine. We have used strychnine for the biochemical characterization and isolation of the glycine receptor of rat spinal cord. Our results show that the glycine receptor is a large membrane protein which contains three different polypeptides. Based on the currently available data we propose a structural model of the glycine receptor and discuss its relation to other proteins of the neuronal membrane that are involved in the transmission of nerve impulses.