Lectins and protein traffic early in the secretory pathway.
Lectins of the early secretory pathway are involved in selective transport of newly synthesized glycoproteins from the endoplasmic reticulum (ER) to the ER-Golgi intermediate compartment (ERGIC). The most prominent cycling lectin is the mannose-binding type I membrane protein ERGIC-53 (ERGIC protein of 53 kDa), a marker for the ERGIC, which functions as a cargo receptor to facilitate export of an increasing number of glycoproteins with different characteristics from the ER. Two ERGIC-53-related proteins, VIP36 (vesicular integral membrane protein 36) and a novel ERGIC-53-like protein, ERGL, are also found in the early secretory pathway. ERGL may act as a regulator of ERGIC-53. Studies of ERGIC-53 continue to provide new insights into the organization and dynamics of the early secretory pathway. Analysis of the cycling of ERGIC-53 uncovered a complex interplay of trafficking signals and revealed novel cytoplasmic ER-export motifs that interact with COP-II coat proteins. These motifs are common to type I and polytopic membrane proteins including presenilin 1 and presenilin 2. The results support the notion that protein export from the ER is selective.
Hauri
Hans-Peter
HP
Biozentrum, Klingelbergstrasse 70, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland. hans-peter.hauri@unibas.ch
Nufer
Oliver
O
Breuza
Lionel
L
Tekaya
Houchaima Ben
HB
Liang
Lu
L
D000595:Amino Acid Sequence; D000818:Animals; D037102:Lectins / Q000737:chemistry / Q000378:metabolism*; D037241:Mannose-Binding Lectins / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D037102:Lectins; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins