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LamB porin
PDB 2mpr EBI.jpg
Structure of maltoporin from Salmonella typhimurium.[1]
Symbol LamB
Pfam PF02264
InterPro IPR003192
SCOP 2mpr
TCDB 1.B.3
OPM superfamily 32
OPM protein 2mpr
CDD cd01346

Maltoporins (or LamB porins) are a family of outer membrane proteins. Maltoporin 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.[2] Maltoporin is a trimeric channel on the bacterial outer membrane. Most pores used for diffusion contain only 16 antiparallel strands, but Maltoporin has 18. The structure of Maltoporin contains long loops and short turns. The long loops are in contact with the cell exterior and the turns are in contact with the periplasm. This channel is involved in sugar transport. The sugar initially binds to the first greasy residue with van der Waals forces. The sugar continues through the channel by guided diffusion of the sugar along the greasy residues which form a "slide". Maltoporin's original name was LamB because it is a bacteriophage lambda receptor. This channel is specific because it has a binding site for maltosaccharides. The affinity of these maltosaccharides to the channel increases as the length of the chain increases.[3]


  1. ^ Meyer JE, Hofnung M, Schulz GE (March 1997). "Structure of maltoporin from Salmonella typhimurium ligated with a nitrophenyl-maltotrioside". J. Mol. Biol. 266 (4): 761–75. doi:10.1006/jmbi.1996.0823. PMID 9102468. 
  2. ^ Schirmer T, Rosenbusch JP, Keller TA, Wang YF (1995). "Structural basis for sugar translocation through maltoporin channels at 3.1 A resolution". Science. 267 (5197): 512–514. doi:10.1126/science.7824948. PMID 7824948. 
  3. ^ Ranquin,A. "Maltoporin: Sugar for physics and biology", Elsevier,Retrieved on 27 April 2004.