ERp29 (Swiss:P52555) is a ubiquitously expressed endoplasmic reticulum protein, and is involved in the processes of protein maturation and protein secretion in this organelle [1,2]. The protein exists as a homodimer, with each monomer being composed of two domains. The N-terminal domain featured in this family is organised into a thioredoxin-like fold that resembles the a domain of human protein disulphide isomerase (PDI) [2]. However, this domain lacks the C-X-X-C motif required for the redox function of PDI; it is therefore thought that ERp29's function is similar to the chaperone function of PDI [2]. The N-terminal domain is exclusively responsible for the homodimerisation of the protein, without covalent linkages or additional contacts with other domains [2].

1: Isolation of ERp29, a novel endoplasmic reticulum protein, from rat enamel cells evidence for a unique role in secretory-protein synthesis. Hubbard MJ, McHugh NJ, Carne DL; Eur J Biochem 2000;267:1945-1957. PMID:10727933

2: Thioredoxin fold as homodimerization module in the putative chaperone ERp29: NMR structures of the domains and experimental model of the 51 kDa dimer. Liepinsh E, Baryshev M, Sharipo A, Ingelman-Sundberg M, Otting G, Mkrtchian S; Structure (Camb) 2001;9:457-471. PMID:11435111