Different expression constructs of Alv-a1-phCl. Alv-a1-pHCl has an N-terminal extension of 37 residues (supplemental Fig. 1A) followed by the N-terminal helix and the LBD. The transmembrane part is formed by the transmembrane helices M1-M4. A, Alv-a1-pHCl full-length protein. B, tAlv-a1-phCl lacks 37 N-terminal residues that likely are disordered. C, tAlv-a1-phCl-AGT. The M3-M4 loop is replaced by the tripeptide AGT. D, thAlv-a1-pHCl, N-terminally truncated by the 37 N-terminal residues and the N-terminal helix. E, thAlv-a1-pHCl-AGT, as the latter, but with the M3-M4 helix replaced by the tripeptide AGT. The constructs in A–C were used for oocyte experiments, and the constructs in B–E were used for Sf9 expression.