This entry represents the beta-alpha-beta-alpha-beta(2) domains common both to bacterial chorismate mutase and to members of the YjgF family. These proteins form trimers with a three-fold symmetry with three closely-packed beta-sheets.
Chorismate mutase (CM, ) is an enzyme of the aromatic amino acid biosynthetic pathway that catalyses the reaction at the branch point of the pathway leading to the three aromatic amino acids, phenylalanine, tryptophan and tyrosine (chorismic acid is the last common intermediate, and CM leads to the L-phenylalanine/L-tyrosine branch). It is part of the shikimate pathway, which is present only in bacteria, fungi and plants. The structure of chorismate mutase enzymes from Bacillus subtilis  and Thermus thermophilus have been solved and were shown to have a catalytic homotrimer, with the active sites being located at the subunit interfaces, where residues from two subunits contribute to each site.
The YjgF family is a large, widely distributed family of proteins of unknown biochemical function that are highly conserved among eubacteria, archaea and eukaryotes. Members include not only the conserved bacterial protein YjgF that displays a homotrimeric structure , but also the regulatory protein YabJ from B. subtilis that is required for adenine-mediated repression of purine biosynthetic genes , the yeast growth inhibitor YER057cp that appears to play a role in the regulation of metabolic pathways and cell differentiation , and the mammalian 14.5 kDa translational inhibitor protein L-PSP (liver perchloric acid-soluble protein) with endoribonucleolytic activity that directly affects mRNA translation and can induce disaggregation of the reticulocyte polysomes into 80 S ribosomes .