Targeting of protein ERGIC-53 to the ER/ERGIC/cis-Golgi recycling pathway

We observed that the COOH-terminal phenylalanines reduce the ER-retrieval capacity of the di-lysine signal and substitution of the phenylalanines in ERGIC-53 by alanines resulted in ER localization. Furthermore, consistent with a pre-Golgi localization, this construct when expressed in LEC-1 cells, which lack the medial-Golgi enzyme N-acetylglucosaminyl transferase, did not become endoglycosidase D sensitive and hence did not reach the Based on our finding that the phenylalanines reduce the pre-Golgi targeting efficiency of the di-lysine ER-retrieval signals, we propose that they reduce the efficiency of recognition of the di-lysine signal by coatomer in the ERGIC, and thereby allow a fraction of ERGIC-53 to be transported to the cis-Golgi.