Synthesis of Multipass Membrane Proteins
Earth History Research Center

1. When a second helical segment of the growing protein, the "Stop-Transfer Membrane-Anchor Sequence" enters the translocon, movement of the protein into the translocon ceases.

2. The first two membrane passages of the protein now move out of the translocon into the membrane itself, firmly anchoring the peptide chain to the membrane.

3. Subsequent synthesis of the peptide continues to accumulate outside of the membrane until another Signal-Anchor Sequence and Stop-Transfer Membrane-Anchor Sequence have been completed.

4. This second set of membrane-soluble helices are then inserted into the Translocon without the aid of the SRP or the SRP receptor.