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The Gram-negative porin 4 (GBP-4) Family [Function: Non-specific diffusion channels] Seed alignment | Full alignment | Pfam page | TC-DB page

General bacterial porins are a family of proteins from the outer membrane of Gram-negative bacteria. The porins act as molecular filters for hydrophilic compounds. They are responsible for the 'molecular sieve' properties of the outer membrane. Porins form large water-filled channels which allow the diffusion of hydrophilic molecules into the periplasmic space. Some porins form general diffusion channels that allow any solutes up to a certain size (that size is known as the exclusion limit) to cross the membrane, while other porins are specific for one particular solute and contain a binding site for that solute inside the pores (these are known as selective porins). As porins are the major outer membrane proteins, they also serve as receptor sites for the binding of phages and bacteriocins. The outer membrane protein OmpU is the most abundant outer membrane protein in V. cholerae, and has been identified as an important virulence factor that is involved in host-cell interaction and recognition, as well as being critical for the survival of the pathogenic V. cholerae in the host body and in harsh environments. The crystal structure of the V. cholerae OmpU trimer is reported to a resolution of 2.2?Å. The protomer forms a 16-ß-stranded barrel with a noncanonical N-terminal coil located in the lumen of the barrel that consists of residues Gly32-Ser42 and is observed to participate in forming the second gate in the pore.

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Literature references

Structural basis for chitin acquisition by marine Vibrio species
Nat Commun. 2018 Jan 15;9(1):220. doi: 10.1038/s41467-017-02523-y.
PMID: 29335469

Crystal structure of the outer membrane protein OmpU from Vibrio cholerae at 2.2? resolution
Acta Crystallogr D Struct Biol. 2018 Jan 1;74(Pt 1):21-29. doi: 10.1107/S2059798317017697. Epub 2018 Jan 1.
PMID: 29372896

Maximized Autotransporter-Mediated Expression (MATE) for Surface Display and Secretion of Recombinant Proteins in Escherichia coli
Food Technol Biotechnol. 2015 Sep;53(3):251-260. doi: 10.17113/ftb.
PMID: 27904356

Amphipols outperform dodecylmaltoside micelles in stabilizing membrane protein structure in the gas phase
Anal Chem. 2015 Jan 20;87(2):1118-26. doi: 10.1021/ac5037022. Epub 2014 Dec 30.
PMID: 25495802

Amphipathic polymers enable the study of functional membrane proteins in the gas phase
Anal Chem. 2012 Nov 20;84(22):9841-7. doi: 10.1021/ac302223s. Epub 2012 Oct 29.
PMID: 23072351

Asymmetric conductivity of engineered porins
Protein Eng. 2002 Oct;15(10):799-804. doi: 10.1093/protein/15.10.799.
PMID: 12468713

Structure of the membrane channel porin from Rhodopseudomonas blastica at 2.0 A resolution
Protein Sci. 1994 Jan;3(1):58-63. doi: 10.1002/pro.5560030108.
PMID: 8142898

Structure of porin refined at 1.8 A resolution
J Mol Biol. 1992 Sep 20;227(2):493-509. doi: 10.1016/0022-2836(92)90903-w.
PMID: 1328651

The bacterial porin superfamily: sequence alignment and structure prediction
Mol Microbiol. 1991 Sep;5(9):2153-64. doi: 10.1111/j.1365-2958.1991.tb02145.x.
PMID: 1662760

Biophysics of the structure and function of porins
Q Rev Biophys. 1990 Nov;23(4):367-403. doi: 10.1017/s003358350000559x.
PMID: 2178269

Permeation of hydrophilic molecules through the outer membrane of gram-negative bacteria. Review on bacterial porins
Eur J Biochem. 1988 Sep 1;176(1):1-19. doi: 10.1111/j.1432-1033.1988.tb14245.x.
PMID: 2901351

Proteins in this family with 3D-structure
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