1IFQ: Sec22b N-Terminal Domain

Intra-cellular membrane fusion is facilitated by the association of SNAREs from opposite membranes into stable alpha-helical bundles. Many SNAREs, in addition to their alpha-helical regions, contain N-terminal domains that likely have essential regulatory functions. To better understand this regulation, we have determined the 2.4-A crystal structure of the 130-amino acid N-terminal domain of mouse Sec22b (mSec22b), a SNARE involved in endoplasmic reticulum/Golgi membrane trafficking. The domain consists of a mixed alpha-helical/beta-sheet fold that resembles a circular permutation of the actin/poly-proline binding protein, profilin, and the GAF/PAS family of regulatory modules. The structure is distinct from the previously characterized N-terminal domain of syntaxin 1A, and, unlike syntaxin 1A, the N-terminal domain of mSec22b has no effect on the rate of SNARE assembly in vitro. An analysis of surface conserved residues reveals a potential protein interaction site. Key residues in this site are distinct in two mammalian Sec22 variants that lack SNARE domains. Finally, sequence analysis indicates that a similar domain is likely present in the endosomal/lysosomal SNARE VAMP7.
PDB ID: 1IFQDownload
MMDB ID: 16182
PDB Deposition Date: 2001/4/13
Updated in MMDB: 2012/10
Experimental Method:
x-ray diffraction
Resolution: 2.4  Å
Source Organism:
Similar Structures:
Biological Unit for 1IFQ: monomeric; determined by author
Molecular Components in 1IFQ
Label Count Molecule
Protein (1 molecule)
Vesicle Trafficking Protein Sec22b(Gene symbol: Sec22b)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

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