FIG. 7.

CcmF is a polytopic cytoplasmic membrane protein. (A) Model for CcmF in the cytoplasmic membrane. This model was generated by analyzing the behavior of CcmF::LacZ (filled triangles if active) and CcmF::PhoA (open squares if active, filled squares if inactive) fusion proteins (see text). The predicted membrane-spanning regions of CcmF are numbered as open circles. The letters H and the boxed WW indicate the predicted location of conserved histidinyl residues that are required for CcmE activity (40) and the tryptophan-rich motif of CcmF, respectively. (B and C) Results of PhoA or LacZ assays on soluble or membrane fractions, respectively, from R. sphaeroides cells that carried hybrid proteins generated at the indicated residue within CcmF.