BAP29 and the related protein BAP31 are endoplasmic reticulum (ER) and ER-vesicle membrane proteins and members of the B-cell receptor-associated protein family. These two proteins are highly homologous and can form homo- and heterodimers. Both BAP29 and BAP31 interact with membrane-bound immunoglobulins (mIgs), such as IgM and IgD, which with Ig-alpha/Ig-beta heterodimers form B cell antigen receptors. Binding of the BAP29/BAP31 heterodimer correlates with the ER retention of non-Ig-alpha/Ig-beta bound mIg complexes, suggesting that BAP29 and BAP31 may act as chaperones for transmembrane regions of various proteins. There are multiple isoforms of BAP29.
has not yet been referenced specifically in any publications.