Glycine cleavage system H protein, mitochondrial (abbreviated as GCSH) is a protein that in humans is encoded by the GCSH gene. Degradation of glycine is brought about by the glycine cleavage system (GCS), which is composed of 4 protein components: P protein (a pyridoxal phosphate-dependent glycine decarboxylase), H protein (a lipoic acid-containing protein; this protein), T protein (a tetrahydrofolate-requiring aminomethyltransferase enzyme), and L protein (a lipoamide dehydrogenase). The H protein shuttles the methylamine group of glycine from the P protein to the T protein. The protein encoded by GCSH gene is the H protein, which transfers the methylamine group of glycine from the P protein to the T protein. Defects in this gene are a cause of nonketotic hyperglycinemia (NKH). Two transcript variants, one protein-coding and the other probably not protein-coding, have been found for this gene. Also, several transcribed and non-transcribed pseudogenes of this gene exist throughout the genome.
