The glycine cleavage system catalyzes the degradation of glycine. The H protein (GCSH) shuttles the methylamine group of glycine from the P protein (GLDC) to the T protein (GCST). Has a pivotal role in the lipoylation of enzymes involved in cellular energetics such as the mitochondrial dihydrolipoyllysine-residue acetyltransferase component of pyruvate dehydrogenase complex (DLAT), and the mitochondrial dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex (DLST) (PubMed:36190515). . This is the function of ENSG00000140905 (GCSH, glycine cleavage system protein H).