The Transport Signal on Sec22 for Packaging into COPII-Coated Vesicles is a Conformational Epitope

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Molecular Cell

DOI:https://doi.org/10.1016/j.molcel.2007.03.017· OSTI ID:930475

Mancias, J; Goldberg, J

The mechanism of cargo concentration into ER-derived vesicles involves interactions between the COPII vesicular coat complex and cargo transport signals-peptide sequences of 10-15 residues. The SNARE protein Sec22 contains a signal that binds the COPII subcomplex Sec23/24 and specifies its endoplasmic reticulum (ER) exit as an unassembled SNARE. The 200 kDa crystal structure of Sec22 bound to Sec23/24 reveals that the transport signal is a folded epitope rather than a conventional short peptide sequence. The NIE segment of the SNARE motif folds against the N-terminal longin domain, and this closed form of Sec22 binds at the Sec23/24 interface. Thus, COPII recognizes unassembled Sec22 via a folded epitope, whereas Sec22 assembly into SNARE complexes would mask the NIE segment. The concept of a conformational epitope as a transport signal suggests packaging mechanisms in which a coat is sensitive to the folded state of a cargo protein or the assembled state of a multiprotein complex.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 930475
• Report Number(s): BNL--81227-2008-JA
• Journal Information: Molecular Cell, Journal Name: Molecular Cell Journal Issue: 3 Vol. 26; ISSN 1097-2765
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARGO
CRYSTAL STRUCTURE
ENDOPLASMIC RETICULUM
PACKAGING
PEPTIDES
PROTEINS
RESIDUES
TRANSPORT
national synchrotron light source