Cytosolic R4op (RAMP4op) and S61βop (Sec61op) but not b5op (cytochrome-b5op) or Ii (invariant chain) can be crosslinked to Asna-1.
A) Outline of the sequences around the TM (black) of R4op, S61βop, b5op and Ii. The sequences are aligned by the relative position of their TM domains. Lysine (K) and cysteine (C) residues that can function in crosslinking with DSS and BMH respectively are indicated. B - E) Crosslinking of the TA proteins and Ii in the RRL: R4op (A), S61βop (B), b5op (C) and Ii (D) were in vitro synthesized in the RRL and small molecules were removed by gel filtration and either DMSO (-) or the crosslinker BMH (B) or DSS (D) were added. The TA proteins were immunoprecipitated with anti-opsin (α-op), anti-Asna-1 (α-Asna-1) or the unrelated anti-Myc (α-Myc) antibodies and characterised by SDS-PAGE and autoradiography. x-Asna-1: crosslinked to Asna-1; The rhombus indicates yet unidentified higher molecular weight complexes.