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). Binds 1 lipoyl cofactor covalently. Interacts with GLDC (By similarity). The glycine cleavage system is composed of four proteins: P (GLDC), T (GCST), L (DLD) and H (GCSH). Belongs to the GcvH family. Was originally (PubMed:3080335 and PubMed:2553401) thought to be a ferredoxin.