Binding immunoglobulin protein (BiP) is a vital protein present in humans essential for the translocation of secreted peptides.
BiP is a molecular chaperone which is present in lumen of ER (endoplasmic reticulum) which binds to the new protein and then translocat into the ER. The protein in ER is maintained under subsequent condition and important for proteinfolding and oligomerization (conversion of a monomer or group of monomer into an oligomer).
Several other functions of BiP are:
ER translocation
ER-associated degradation (ERAD)
UPR pathway
Hence, BiP is a chaperone, it is important for proteinfolding and oligomerization.