Jansen, B., Hartgers, F.C. et al., Ramirez Gaite, M.
TM7SF4 (also known as dendritic cell-specific transmembrane protein or DC-STAMP) is expressed in dendritic cells (DCs), the professional antigen-presenting cells of our immune system . TM7SF4 is localized to the endoplasmic reticulum , but upon encountering danger signals that evoke innate immune responses, it translocates to the Golgi. This process is regulated by OS9, a protein involved in ER-to-Golgi transport  . TM7SF4 also binds to an ER-resident transcription factor (CREB3, also known as LUMAN), which needs to be transported to the Golgi to be activated in a process called regulated intramembrane proteolysis. Although the role of TM7SF4 is not exactly known, it is likely an important regulator of CREB3. Intriguingly, OS9 and CREB3 can also interact with each other, suggesting that TM7SF4, OS9 and CREB consist in a complex in the ER that dissociates into OS9 and TM7SF4/CREB3 upon triggering of innate immune signaling. This ultimately leads to the production of active, nuclear CREB3, which drives or represses gene expression and presumably modulates innate immune responses .