Figure 1. DHCR24 TMD and membrane topology predictions.

(A) A hydropathy profile of DHCR24 using the method of Kyte and Doolittle [15], returned by ProtScale with a window size of 19. The recommended threshold for the detection of TMDs is indicated by the dotted red line (1.6) [15], with peak regions of hydrophobicity above this marked in red (A and B). The GRAVY score is indicated by the solid blue line (−0.061). Predicted TMDs based on the apparent free energy difference for ER membrane insertion by the Sec61 translocon (ΔG_mi) below the 1.6 threshold are marked in blue (c, d, e) (B) Putative TMDs and their probability based on ΔG_mi [24]. (C) TMD predictions by the five TOPCONS algorithms: SCAMPI-seq and SCAMPI-msa [25], PRODIV and PRO [26] and OCTOPUS [27] and the TOPCONS global prediction (TOPCONS consensus) [25]. Potential TMDs are boxed grey (cytosol → lumen) or white (lumen → cytosol). Dotted grey lines indicate DHCR24 truncations, which are used in Figures 3–5. (D) DHCR24 membrane topology as predicted by the TMHMM server [16], with the probability of cytosol, membrane or lumenal location in red, grey or blue, respectively.