PROTEIN INSERTION INTO THE ENDOPLASMIC-RETICULUM OF PERMEABILIZED CELLS

We have established efficient translocation of newly synthesized prote ins into the endoplasmic reticulum of permeabilized Mel Juso cells, By site-specific photo-crosslinking we show that translocating polypepti de chains contact the same components of permeabilized cells ER as in dog pancreas rough microsomes, This cellular assay system has the pote ntial to overcome the limitations of isolated microsomes in investigat ing the molecular environment of a newly synthesized protein after the y have left the ER translocation site.