Figure 6: Transition between the two states and intervention by disulfide crosslinking studies.
From: Conformational states of the full-length glucagon receptor
(a) Modes 1 and 2 of the NMA on the open structure (top, orange arrow), and modes 3 and 4 of the NMA on the closed structure (bottom, yellow arrow) based on representative open state (confopen) and closed state (confclosed) structures (Fig. 3). The vectors representing both the amplitudes and directions of residues during the conformational changes are mapped on the ECD. (b) Selected residue pair H372ECL3–H89ECD for cysteine substitution is shown in the closed state of apo-GCGR, with the average Cβ–Cβ distance in the last 1,000 ns simulation. (c) Time dependences of the Cβ–Cβ distance between H372ECL3 and H89ECD in the MD simulations on glucagon-GCGR (blue) and apo-GCGR (red). (d) MS/MS spectra of the HCD fragmentation of the doubly charged disulfide-containing peptide are shown; b, y, B and Y indicate types of fragment ions. Graphical fragment map correlates the fragmentation ions to the peptide sequence in which the disulfide-linked cysteine residues C89 and C372 are shown in red. The top-right panel shows a LC-MS analysis-extracted ion chromatogram of GCGR from Spodoptera frugiperda (Sf9) cells with chymotrypsin and trypsin digestion, representing the doubly charged crosslinked peptide between YLPWHC(89)K and AFVTDEC(372)AQGTLR through a disulfide bond.
