The SIL1 gene encodes the nucleotide exchange factor SIL1 for the endoplasmic reticulum resident heat-shock protein 70 chaperone BiP (also known as GRP78). As a nucleotide exchange factor, SIL1 induces ADP release and ATP binding of BiP. BiP is encoded by the HSPA5 gene; it functions in protein translocation, synthesis, and quality control and senses and responds to stressful cellular conditions.