GCDH is part of the acyl-CoA dehydrogenase family. GCDH is localized in the mitochondrial matrix as a homotetramer of 45-kD subunits. GCDH catalyzes the oxidative decarboxylation of glutaryl-CoA to crotonyl-CoA and CO(2) in the degradative pathway of L-lysine, L-hydroxylysine, and L-tryptophan metabolism. GCDH uses electron transfer flavoprotein as its electron acceptor.