Domain

Porin domain, Gram-negative type (IPR033900)

Short name: Gram_neg_porin_domain

Overlapping homologous superfamilies

Domain relationships

None.

Description

Porins form aqueous channels for the diffusion of small hydrophillic molecules across the outer membrane [PMID: 14665678]. Individual 16-strand anti-parallel beta-barrels form a central pore, and trimerizes through mainly hydrophobic interactions at the interface. Trimers are stabilized by hytrophillic clamping of Loop L2. Loop 3 bends into the pore, creating an elliptical constriction of about 7 x 11 angstroms, large enough to allow passage of a glucose molecule without steric hindrance. Removal of the C-terminal residue (usually Phe) destabilizes the trimer and removal of the 16th beta-sheet abolishes trimerization. Unlike typical membrane proteins, porins lack long hydrophobic stretches. Short turns are found at the smooth, periplasmic end, longer irregular loops are found at the rough, extracellular end. The C-terminal residue forms a salt bridge with the N terminus [PMID: 1380671].

This entry represents the structural domain found in Gram-negative bacterial porins.

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0015288 porin activity

Cellular Component

GO:0016020 membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
CDD