A 12-RESIDUE-LONG POLYLEUCINE TAIL IS SUFFICIENT TO ANCHOR SYNAPTOBREVIN TO THE ENDOPLASMIC-RETICULUM MEMBRANE

Synaptobrevin is a tail-anchored protein with a hydrophobic C-terminal transmembrane segment that inserts into the endoplasmic reticulum mem brane independently of the SRP/Sec61p pathway. Here, we show that idea lized hydrophobic segments composed of 11-17 leucines and 1 valine fun ction as insertion signals in vitro, whereas shorter segments do not. These results suggest that there are no specific requirements beyond o verall hydrophobicity for C-terminal endoplasmic reticulum insertion s ignals.