FIG. 1.

Structure of Tar and Tap chimeras. (A) Primary structures. Regions derived from Tar are shown in white, whereas regions derived from Tap are hatched. The TM regions are depicted as solid black rectangles. The positions of glutamate residues subject to methylation are indicated with asterisks above Tar: three methylation sites are in the K1 tryptic peptide, and one methylation site is in the R1 tryptic peptide. The NWETF motif for binding of CheR is depicted as a bold black line above the right-hand (carboxyl-terminal) end of Tar. The periplasmic and cytoplasmic regions of Tar are also labeled. The protein-equivalent positions of the naturally occurring (tar) or introduced (tap) NdeI restriction site and of the introduced NheI restriction site are indicated beneath Tart. (B) Membrane topology of the chimeric Tapr receptor.