This family consists of proline racemase (EC 5.1.1.4) proteins which catalyse the interconversion of L- and D-proline in bacteria [1]. This family also contains several similar eukaryotic proteins including Swiss:Q9NCP4 a sequence with B-cell mitogenic properties which has been characterised as a co-factor-independent proline racemase [2].

1: Energetics of proline racemase: racemization of unlabeled proline in the unsaturated, saturated, and oversaturated regimes. Fisher LM, Albery WJ, Knowles JR; Biochemistry 1986;25:2529-2537. PMID:3755058

2: A B-cell mitogen from a pathogenic trypanosome is a eukaryotic proline racemase. Reina-San-Martin B, Degrave W, Rougeot C, Cosson A, Chamond N, Cordeiro-Da-Silva A, Arala-Chaves M, Coutinho A, Minoprio P; Nat Med 2000;6:890-897. PMID:10932226