Glycine is an amino acid that has a single hydrogen atom as its side chain. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (GGU, GGC, GGA, GGG). Glycine is integral to the formation of alpha-helices in secondary protein structure due to its compact form. For the same reason, it is the most abundant amino acid in collagen triple-helices. Glycine is also an inhibitory neurotransmitter – interference with its release within the spinal cord can cause spastic paralysis due to uninhibited muscle contraction.

Many researchers have focused on increasing glycine levels in synapses to find an effective treatment for schizophrenia. This could be done using inhibitors targeting Glycine Transporter 1 (GlyT1), a protein that sits in neuronal cell membranes and is responsible for the uptake of glycine into neurons. However, the development of such drugs has been hampered because the 3D structure of GlyT1 was not known.