Roepe P D, Consler T G, Menezes M E, Kaback H R
Department of Physiology, Howard Hughes Medical Institute, University of California, Los Angeles 90024-1570.
Res Microbiol. 1990 Mar-Apr;141(3):290-308. doi: 10.1016/0923-2508(90)90003-9.
In this communication, we summarize site-directed mutagenesis studies of the lac permease from Escherichia coli, a prototypic H(+)-coupled active transport protein. We classify mutant permeases by phenotype, and suggest possible roles for some individual residues in the mechanism of H+/lactose symport. Although high-resolution structural information is not presently available, kinetic analysis of the partial reactions catalysed by the mutant permeases, as well as biophysical studies, suggest an evolving model for the mechanism of H+/lactose symport.
