Porin, LamB-type (IPR003192)

Short name: Porin_LamB

Overlapping homologous superfamilies

Family relationships

  • Porin, LamB-type (IPR003192)


Maltoporin (LamB protein) forms a trimeric structure which facilitates the diffusion of maltodextrins across the outer membrane of Gram-negative bacteria. The membrane channel is formed by an antiparallel beta-barrel [PMID: 7824948]. Loop 3 folds into the core to constrict pore size. Long irregular loops are found on the extracelllular side, while short turns are in the periplasm. Tightly-bound water molecules are found in the eyelet of the passage, and only substrates that can displace and replace the broken hydrogen bonds are likely to enter the pore. Loops 4, 6, and 9 have the greatest mobility and are highly variable; these are postulated to attract maltodextrins [PMID: 9102468].

The porin LamB family also includes porin BglH, which may be a sugar porin with a broad carbohydrate specificity, and sucrose porin [PMID: 1649946, PMID: 9437428].

GO terms

Biological Process

GO:0034219 carbohydrate transmembrane transport

Molecular Function

GO:0015288 porin activity

Cellular Component

GO:0016020 membrane

Contributing signatures

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