Figure 1: The overall structure and masses of the full-length mitochondrial aspartate/glutamate carrier and its domains.

(a) The three-domain structure of the aspartate/glutamate carrier isoform 2, citrin, consisting of the N-terminal domain (residues 1–319), carrier domain (residues 320–612) and the C-terminal domain (residues 613–675). The α-helices of EF-hands 1–8 in the N-terminal domain (blue lines) are shown in a rainbow colour scheme. The calcium ion, bound by EF-hand 2, is indicated by a green circle. The α-helices of the transporter domain are shown in light grey, based on secondary-structure predictions and similarity to the structures of the bovine²¹ and yeast ADP/ATP carriers²². Red dotted vertical lines highlight the borders of the three homologous repeats. The α-helix of the C-terminal domain is shown in wheat colour. Light scattering traces of (b) citrin in lauryl maltose neopentyl glycol, (c) carrier domain of citrin (black line) and the yeast ADP/ATP carrier Aac2p in dodecyl-maltoside (grey dashed line), (d) N- and C-terminal domain fusion of citrin, and (e) N-terminal domain (orange) and N- and C-terminal domain fusion of aralar (black). The masses of the proteins, as determined by SEC-MALLS, are shown in red. The masses of the associated protein-detergent-lipid micelles (PDL) and detergent-lipid micelles (DL) are shown in green and blue, respectively, where relevant.