FIG. 1.

Aer domain organization. The scale at the top denotes residue numbers in the Aer protein. For this study, genetically silent restriction sites were created at aer codons 101, 210, and 270 in order to manipulate the F1 and HAMP portions of the coding region. The structure of the F1 segment of the Aer protein is unknown, whereas the HAMP region is predicted to consist of two amphipathic α-helices (AS-1 and AS-2) joined by a connector of unknown structure. The first and last residues of AS-1 and AS-2, based on HAMP sequence alignments (4, 5, 27), are indicated. The residue boundaries for the HAMP connector segment are slight modifications of those reported by Ma et al. (16).