InterPro domain: IPR006175

The YjgF/YER057c/UK114 family (also known as the Rid family) of proteins is conserved in all domains of life [ 1 ]. A phylogenetic analysis applied by Lambrecht et al. has divided the Rid family into a widely distributed archetypal RidA (YjgF) subfamily and seven other subfamilies (Rid1 to Rid7) that are largely confined to bacteria and often co-occur in the same organism with RidA and each other [ 2 ]. Although the family members share high levels of protein sequence and structue similarity, their functions vary widely across different species [ 3 ].

Structurally, these proteins are homotrimers with clefts between the monomeric subunits that are proposed to have some functional relevance [ 4 , 5 , 6 ].

This family includes:

• YjgF (also known as RidA or 2-iminobutanoate/2-iminopropanoate deaminase), which displays enamine/imine deaminase activity and can accelerate the release of ammonia from reactive enamine/imine intermediates of the pyridoxal 5'-phosphate-dependent threonine dehydratase (IlvA) [ 7 , 7 ]
• the yeast growth inhibitor YER057c (protein HMF1) that appears to play a role in the regulation of metabolic pathways and cell differentiation [ 8 ]
• the mammalian 14.5kDa translational inhibitor protein UK114, also known as 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 [ 9 ]
• RutC from E. coli, which is essential for growth on uracil as sole nitrogen source and is thought to reduce aminoacrylate peracid to aminoacrylate [ 10 ]
• YabJ from B. subtilis, which is required for adenine-mediated repression of purine biosynthetic genes [ 11 ]

1. Conserved YjgF protein family deaminates reactive enamine/imine intermediates of pyridoxal 5'-phosphate (PLP)-dependent enzyme reactions. J. Biol. Chem. 287, 3454-61
2. Genomic and experimental evidence for multiple metabolic functions in the RidA/YjgF/YER057c/UK114 (Rid) protein family. BMC Genomics 16, 382
3. Diurnal heart rate and body temperature in marmosets. Am. J. Phys. Anthropol. 38, 339-42
4. Mycobacterium tuberculosis Rv2704 is a member of the YjgF/YER057c/UK114 family. Proteins 78, 773-8
5. X-ray structure of Saccharomyces cerevisiae homologous mitochondrial matrix factor 1 (Hmf1). Proteins 48, 431-6
6. A test case for structure-based functional assignment: the 1.2 A crystal structure of the yjgF gene product from Escherichia coli. Protein Sci. 8, 2428-37
7. YjgF is required for isoleucine biosynthesis when Salmonella enterica is grown on pyruvate medium. J. Bacteriol. 190, 3057-62
8. A member of the YER057c/yjgf/Uk114 family links isoleucine biosynthesis and intact mitochondria maintenance in Saccharomyces cerevisiae. Genes Cells 6, 507-17
9. Ribonuclease activity of rat liver perchloric acid-soluble protein, a potent inhibitor of protein synthesis. J. Biol. Chem. 274, 20688-92
10. The Rut pathway for pyrimidine degradation: novel chemistry and toxicity problems. J. Bacteriol. 192, 4089-102
11. Crystal structure of Bacillus subtilis YabJ, a purine regulatory protein and member of the highly conserved YjgF family. Proc. Natl. Acad. Sci. U.S.A. 96, 13074-9