This domain is found in the D-3-phosphoglycerate dehydrogenase enzyme. In the structure of the Mycobacterium tuberculosis enzyme this domain was described as the intervening domain, also known as the allosteric substrate binding domain (ASB) [1,2,3]. The intervening domain between the substrate-binding and regulatory domains is not present in E. coli PGDH. This domain is closely related to Pfam:PF03315. It serves as an anion-binding site and may function as an allosteric site for the control of enzyme activity [3].

1: Crystal structure of Mycobacterium tuberculosis D-3-phosphoglycerate dehydrogenase: extreme asymmetry in a tetramer of identical subunits. Dey S, Grant GA, Sacchettini JC; J Biol Chem. 2005;280:14892-14899. PMID:15668249

2: Structural analysis of substrate and effector binding in Mycobacterium tuberculosis D-3-phosphoglycerate dehydrogenase. Dey S, Burton RL, Grant GA, Sacchettini JC; Biochemistry. 2008;47:8271-8282. PMID:18627175

3: Contrasting catalytic and allosteric mechanisms for phosphoglycerate dehydrogenases. Grant GA; Arch Biochem Biophys. 2012;519:175-185. PMID:22023909