SSF82919

Zn-finger domain of Sec23/24

SUPERFAMILY entry
Member databaseSUPERFAMILY
SUPERFAMILY typehomologous superfamily

Description
Imported from IPR036174

Zinc finger (Znf) domains are relatively small protein motifs which contain multiple finger-like protrusions that make tandem contacts with their target molecule. Some of these domains bind zinc, but many do not; instead binding other metals such as iron, or no metal at all. For example, some family members form salt bridges to stabilise the finger-like folds. They were first identified as a DNA-binding motif in transcription factor TFIIIA from Xenopus laevis (African clawed frog), however they are now recognised to bind DNA, RNA, protein and/or lipid substrates
[6, 7, 8, 5, 4]
. Their binding properties depend on the amino acid sequence of the finger domains and of the linker between fingers, as well as on the higher-order structures and the number of fingers. Znf domains are often found in clusters, where fingers can have different binding specificities. There are many superfamilies of Znf motifs, varying in both sequence and structure. They display considerable versatility in binding modes, even between members of the same class (e.g. some bind DNA, others protein), suggesting that Znf motifs are stable scaffolds that have evolved specialised functions. For example, Znf-containing proteins function in gene transcription, translation, mRNA trafficking, cytoskeleton organisation, epithelial development, cell adhesion, protein folding, chromatin remodelling and zinc sensing, to name but a few
[2]
. Zinc-binding motifs are stable structures, and they rarely undergo conformational changes upon binding their target.

COPII (coat protein complex II)-coated vesicles carry proteins from the endoplasmic reticulum (ER) to the Golgi complex
[3]
. COPII-coated vesicles form on the ER by the stepwise recruitment of three cytosolic components: Sar1-GTP to initiate coat formation, Sec23/24 heterodimer to select SNARE and cargo molecules, and Sec13/31 to induce coat polymerisation and membrane deformation
[1]
.

Sec23 p and Sec24p are structurally related, folding into five distinct domains: a β-barrel, a zinc-finger, an α/β trunk domain (
IPR006896
), an all-helical region (
IPR006900
), and a C-terminal gelsolin-like domain (
IPR007123
). This entry describes an approximately 55-residue Sec23/24 zinc-binding domain, which lies against the β-barrel at the periphery of the complex.

References
Imported from IPR036174

1.Structure of the Sec23/24-Sar1 pre-budding complex of the COPII vesicle coat. Bi X, Corpina RA, Goldberg J. Nature 419, 271-7, (2002). View articlePMID: 12239560

2.Zinc finger proteins: new insights into structural and functional diversity. Laity JH, Lee BM, Wright PE. Curr. Opin. Struct. Biol. 11, 39-46, (2001). View articlePMID: 11179890

3.Structure of the Sec23p/24p and Sec13p/31p complexes of COPII. Lederkremer GZ, Cheng Y, Petre BM, Vogan E, Springer S, Schekman R, Walz T, Kirchhausen T. Proc. Natl. Acad. Sci. U.S.A. 98, 10704-9, (2001). View articlePMID: 11535824

4.Zinc fingers--folds for many occasions. Matthews JM, Sunde M. IUBMB Life 54, 351-5, (2002). View articlePMID: 12665246

5.Sticky fingers: zinc-fingers as protein-recognition motifs. Gamsjaeger R, Liew CK, Loughlin FE, Crossley M, Mackay JP. Trends Biochem. Sci. 32, 63-70, (2007). View articlePMID: 17210253

6.Zinc finger peptides for the regulation of gene expression. Klug A. J. Mol. Biol. 293, 215-8, (1999). View articlePMID: 10529348

7.Multiple modes of RNA recognition by zinc finger proteins. Hall TM. Curr. Opin. Struct. Biol. 15, 367-73, (2005). View articlePMID: 15963892

8.Zinc finger proteins: getting a grip on RNA. Brown RS. Curr. Opin. Struct. Biol. 15, 94-8, (2005). View articlePMID: 15718139

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