Specific labeling and partial purification of the M protein, a component of the beta-galactoside transport system of Escherichia coli.

Abstract

The particulate fraction in which the M-protein is localized contains the cell wall membrane complex as well as some ribosomal material. The amount of ribosomal material can be reduced if the fraction is collected and washed by centrifugation at lower speeds without affecting the content of M-protein. Much of the cell wall of E. coli may be removed by treatment with lysozyme-ethylene diamine-tetraacetic acid (EDTA) without loss of the [beta]-galactoside transport system. The M-protein is probably a constituent of the spheroplast membrane. Whether the M-protein is present in various y-mutants and, whether its properties are different from those of the protein found in wild-type cells should be determined.