3EG9: Crystal Structure Of The Mammalian Copii-coat Protein Sec23/24 Bound To The Transport Signal Sequence Of Membrin

Citation:
Abstract
Genomic analysis shows that the increased complexity of trafficking pathways in mammalian cells involves an expansion of the number of SNARE, Rab and COP proteins. Thus, the human genome encodes four forms of Sec24, the cargo selection subunit of the COPII vesicular coat, and this is proposed to increase the range of cargo accommodated by human COPII-coated vesicles. In this study, we combined X-ray crystallographic and biochemical analysis with functional assays of cargo packaging into COPII vesicles to establish molecular mechanisms for cargo discrimination by human Sec24 subunits. A conserved IxM packaging signal binds in a surface groove of Sec24c and Sec24d, but the groove is occluded in the Sec24a and Sec24b subunits. Conversely, LxxLE class transport signals and the DxE signal of VSV glycoprotein are selectively bound by Sec24a and Sec24b subunits. A comparative analysis of crystal structures of the four human Sec24 isoforms establishes the structural determinants for discrimination among these transport signals, and provides a framework to understand how an expansion of coat subunits extends the range of cargo proteins packaged into COPII-coated vesicles.
PDB ID: 3EG9Download
MMDB ID: 67502
PDB Deposition Date: 2008/9/10
Updated in MMDB: 2008/10
Experimental Method:
x-ray diffraction
Resolution: 3  Å
Source Organism:
synthetic construct
Similar Structures:
Biological Unit for 3EG9: trimeric; determined by author and by software (PISA)
Molecular Components in 3EG9
Label Count Molecule
Proteins (3 molecules)
1
Protein Transport Protein Sec23a(Gene symbol: SEC23A)
Molecule annotation
1
Sec24 Related Gene Family, Member D
Molecule annotation
1
Peptide
Molecule annotation
Chemicals (2 molecules)
1
2
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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