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) (By similarity). Binds 1 lipoyl cofactor covalently. The glycine cleavage system is composed of four proteins: P (GLDC), T (GCST), L (DLD) and H (GCSH). Interacts with GLDC (By similarity). Belongs to the GcvH family.