FIG. 5.

2D SDS-PAGE analysis of membrane-associated proteins. Membrane-associated proteins were prepared from cultures of strain P1432 grown to mid-exponential phase without acid adaptation (A), grown to mid-exponential phase and acid adapted at pH 5.0 for 1 h (B), or grown to stationary phase overnight (C). Spots which showed reproducible differences (for each gel, n = 3) in expression are circled and labelled 1 to 13 (see text for details). The positions of the molecular mass standards are indicated in kilodaltons on the vertical axes, and the approximate pI scale is indicated on the horizontal axes.