The glycine cleavage system catalyzes the degradation of glycine. The P protein (GLDC) binds the alpha-amino group of glycine through its pyridoxal phosphate cofactor; CO(2) is released and the remaining methylamine moiety is then transferred to the lipoamide cofactor of the H protein (GCSH). (R)-N(6)-lipoyl-L-lysyl-[glycine-cleavage complex H protein] + glycine + H(+) = (R)-N(6)-(S(8)-aminomethyldihydrolipoyl)-L-lysyl-[glycine-cleavage complex H protein] + CO2 Stimulated by lipoic acid. Inhibited in presence of methylamine. Homodimer. Interacts with GCSH. The glycine cleavage system is composed of four proteins: P (GLDC), T (GCST), L (DLD) and H (GCSH). Liver (at protein level). Belongs to the GcvP family.