This is the barrel domain of pyruvate kinases. This domain represents the beta/alpha barrel and the small beta-barrel domain inserted within it. The active site is found in a cleft between the two domains [1,2,3,4].

1: Ligand-induced domain movement in pyruvate kinase: structure of the enzyme from rabbit muscle with Mg2+, K+, and L-phospholactate at 2.7 A resolution. Larsen TM, Benning MM, Wesenberg GE, Rayment I, Reed GH; Arch Biochem Biophys 1997;345:199-206. PMID:9308890

2: Pyruvate kinase: current status of regulatory and functional properties. Munoz ME, Ponce E; Comp Biochem Physiol B Biochem Mol Biol. 2003;135:197-218. PMID:12798932

3: Structure and function of human erythrocyte pyruvate kinase. Molecular basis of nonspherocytic hemolytic anemia. Valentini G, Chiarelli LR, Fortin R, Dolzan M, Galizzi A, Abraham DJ, Wang C, Bianchi P, Zanella A, Mattevi A; J Biol Chem. 2002;277:23807-23814. PMID:11960989

4: An allostatic mechanism for M2 pyruvate kinase as an amino-acid sensor. Yuan M, McNae IW, Chen Y, Blackburn EA, Wear MA, Michels PAM, Fothergill-Gilmore LA, Hupp T, Walkinshaw MD; Biochem J. 2018;475:1821-1837. PMID:29748232