May play a role in anterograde transport of membrane proteins from the endoplasmic reticulum to the Golgi. May be involved in CASP8-mediated apoptosis (By similarity). Homodimer (PubMed:25327138). Heterodimer with BCAP31. Binds CASP8 (isoform 9) as a complex containing BCAP31, BCAP29, BCL2 and/or BCL2L1. Interacts with VAMP3, VAMP1 and membrane IgD immunoglobulins. May interact with ACTG1 and non-muscle myosin II (By similarity). Belongs to the BCAP29/BCAP31 family.