Proteins in this entry occur in archaea, bacteria and eukaryotes. They are encoded by genes which are often co-transcribed with proline biosysnthesis genes [PMID:10496079], although their function in vivo has not yet been demonstrated.

The structure of the yeast protein YBL036C (SWISSPROT: P38197) has been determined to a resolution of 2.0 A [PMID:12499548]. Similar in structure to the N-terminal domains of alanine racemase and ornithine decarboxylase, it forms a TIM barrel fold which begins with a long N-terminal helix, rather than the classical beta strand found at the beginning of most other TIM barrels. Unlike alanine racemase and ornithine decarboxylase, which are two-domain dimeric proteins, the yeast protein is a single domain monomer. A pyridoxal 5'-phosphate cofactor is covalently bound towards the C-terminal end of the barrel, which is the usual active site in TIM-barrel folds. Some racemase activity was observed for this protein and it was suggested by the authors that it may function as a general racemase [PMID:12499548].