The size of the lactose permease derived from rotational diffusion measurements.
The lactose permease of Escherichia coli was labeled with eosinyl-maleimide, reconstituted into vesicles of dimyristoylphosphatidylcholine and subjected to time-dependent phosphorescence anisotropy measurements in order to determine the rotational diffusion coefficient. By comparison with bacteriorhodopsin, the diffusion coefficient is evaluated in terms of an effective radius of the lactose permease in the plane of the membrane. This radius amounts to 20 +/- 2 A which implies that the lactose permease is a monomer. The monomeric state is maintained in the presence of a membrane potential.
D004058:Diffusion; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D066298:In Vitro Techniques; D008081:Liposomes; D046911:Macromolecular Substances; D008564:Membrane Potentials; D026901:Membrane Transport Proteins; D008970:Molecular Weight; D009004:Monosaccharide Transport Proteins; D010713:Phosphatidylcholines; D027981:Symporters; D013696:Temperature
D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D008081:Liposomes; D046911:Macromolecular Substances; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D010713:Phosphatidylcholines; D027981:Symporters; C021499:lactose permease