title: Periplasmic maltose-binding protein confers specificity on the outer membrane maltose pore of Escherichia coli.
abstract: ompB mutants of Escherichia coli K-12 are markedly deficient in porin in their outer membrane. This results in a decreased rate of uptake for many substrates: the maltose pore (lambda receptor) can in some circumstances, in the absence of the periplasmic maltose-binding protein, compensate for the consequent defects in permeability to lactose, mannitol, glycylglycyl-L-valine, and tri-L-ornithine. It is postulated that the maltose-binding protein associates with the maltose pore and confers on it the specificity for maltose, and that the absence of the maltose-binding protein leaves the pore open and results in enhanced transmembrane diffusion of molecules other than maltose. This paper presents evidence to support this hypothesis.
mesh_terms: D010582:Bacteriophage lambda; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D007785:Lactose / Q000378:metabolism; D008320:Maltose / Q000378:metabolism*; D008353:Mannitol / Q000378:metabolism; D009154:Mutation; D010455:Peptides / Q000378:metabolism; D011991:Receptors, Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D010455:Peptides; D011991:Receptors, Virus; D008353:Mannitol; D008320:Maltose; D007785:Lactose