Pyrroline-5-carboxylate reductase consists of two domains, an N-terminal catalytic domain (Pfam:PF03807) and a C-terminal dimerisation domain. This is the dimerisation domain [1].

1: Crystal structures of delta1-pyrroline-5-carboxylate reductase from human pathogens Neisseria meningitides and Streptococcus pyogenes. Nocek B, Chang C, Li H, Lezondra L, Holzle D, Collart F, Joachimiak A; J Mol Biol. 2005;354:91-106. PMID:16233902