ERp29 is a ubiquitously expressed endoplasmic reticulum protein, and is involved in the processes of protein maturation and protein secretion in this organelle. The protein exists as a homodimer, with each monomer being composed of two domains. The N-terminal domain featured in this family is organized into a thioredoxin-like fold that resembles the a domain of human protein disulphide isomerase (PDI). 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. The N-terminal domain is exclusively responsible for the homodimerization of the protein, without covalent linkages or additional contacts with other domains.