FIGURE 3.

Proteolytic destruction of products that are detrimental to protein translocation. (A) Lon protease prevents mislocalized Sec substrates from inhibiting the Sec machinery by turning over Sec substrates that accumulate in the cytoplasm. (B) FtsH degrades SecYEG channels that have been jammed (e.g., by arrested ribosomes synthesizing Sec substrate proteins). (C) The peptidase PrlC could potentially remove the signal sequences from the Sec substrate proteins that have accumulated in the cytoplasm and prevent them from competitively inhibiting translocation.