Fig. 1: REEPs form dimers.

a Proposed membrane topology of the REEPs and Rtns. The four hydrophobic transmembrane segments (TMs) are numbered and shown in blue; the predicted amphipathic helix (APH) is shown in purple. b SEC of S. japonicus Yop1 and Xenopus laevis REEP5 purified in the detergent DDM. The experiment was performed four times. The top panel shows the absorbance at 280 nm. Fractions of the eluate were analyzed by SDS-PAGE, and stained with Coomassie blue (lower panels). c SEC-MALS analysis of purified REEP5 and Yop1-3C-SBP, analyzed in DDM. Absorbance at 280 nm (UV) was normalized relative to the maximum reading of REEP5 (left axis). The calculated protein mass is shown across the peaks (right axis). The table on top shows the calculated and predicted monomer masses. d SBP-tagged full-length Yop1 or Yop1 lacking the APH (Yop1ΔAPH) was co-expressed with His-tagged full-length Yop1 or Yop1ΔAPH. DDM-solubilized membrane fractions were incubated with streptavidin beads and the bound material analyzed by SDS-PAGE and Coomassie-blue staining. As a control, SBP- and His-tagged Yop1 were individually expressed and purified. The experiment was performed three times.