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The Maltoporin (LamB) Family [Function: Specific diffusion channels] Seed alignment | Full alignment | Pfam page | Pfam Wiki page | TC-DB page

The Maltoporin (LamB) Family includes the well characterized maltoporins of Escherichia coli and Salmonella typhimurium as well as the sucrose-specific porin of Salmonella typhimurium, whose 3D structures have been resolved by X-ray diffraction. These porins form trimers but, in contrast to proteins belonging to other bacterial porin families which consist of 16 ß-stranded ß-barrels, they consist of an 18 ß-stranded ß-barrel. Despite the wider barrel compared to other porins, sugar-specific porins exhibit a narrower channel, showing only a small fraction of the ionic conductance of the latter porins. There is also evidence that in most cases, the N-terminal residues form a coiled-coil of alpha helices facilitating low-affinity sugar binding and supramolecular stabilisation.

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Literature references

A New Strain Collection for Improved Expression of Outer Membrane Proteins
Front Cell Infect Microbiol. 2017 Nov 7;7:464. doi: 10.3389/fcimb.2017.00464. eCollection 2017.
PMID: 29164072

Maltoporin LamB Unfolds ß Hairpins along Mechanical Stress-Dependent Unfolding Pathways
Structure. 2017 Jul 5;25(7):1139-1144.e2. doi: 10.1016/j.str.2017.05.010. Epub 2017 Jun 15.
PMID: 28625789

Structural basis for outer membrane sugar uptake in pseudomonads
J Biol Chem. 2012 Nov 30;287(49):41044-52. doi: 10.1074/jbc.M112.408518. Epub 2012 Oct 12.
PMID: 23066028

Folding studies of purified LamB protein, the maltoporin from the Escherichia coli outer membrane: trimer dissociation can be separated from unfolding
Biochim Biophys Acta. 2011 Sep;1808(9):2206-13. doi: 10.1016/j.bbamem.2011.05.013. Epub 2011 May 24.
PMID: 21640073

Structure and functional characterization of the periplasmic N-terminal polypeptide domain of the sugar-specific ion channel protein (ScrY porin)
Protein Sci. 2002 Jun;11(6):1565-74. doi: 10.1110/ps.2760102.
PMID: 12021455

Structure of the sucrose-specific porin ScrY from Salmonella typhimurium and its complex with sucrose
Nat Struct Biol. 1998 Jan;5(1):37-46. doi: 10.1038/nsb0198-37.
PMID: 9437428

Channel specificity: structural basis for sugar discrimination and differential flux rates in maltoporin
J Mol Biol. 1997 Sep 12;272(1):56-63. doi: 10.1006/jmbi.1997.1224.
PMID: 9299337

Structure of maltoporin from Salmonella typhimurium ligated with a nitrophenyl-maltotrioside
J Mol Biol. 1997 Mar 7;266(4):761-75. doi: 10.1006/jmbi.1996.0823.
PMID: 9102468

Structural basis for sugar translocation through maltoporin channels at 3.1 A resolution
Science. 1995 Jan 27;267(5197):512-4. doi: 10.1126/science.7824948.
PMID: 7824948

Crystallization and preliminary X-ray diffraction analysis of ScrY, a specific bacterial outer membrane porin
J Mol Biol. 1993 Jan 5;229(1):258-62. doi: 10.1006/jmbi.1993.1028.
PMID: 8421311

Proteins in this family with 3D-structure
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