Figure 1. mRNA diagrams, membrane topologies, and possible engagement with the transclocon of the ER membrane proteins used in this study.

(A) Schematic diagrams of mRNAs and (B) membrane topologies of the ER membrane proteins studied here. Final destinations of the membrane proteins are indicated in parentheses. (C) Possible engagement of nonstop ER membrane proteins with the Sec61 translocon channel. Mmm1: A protein that follows the N-terminus translocation pathway mediated by the TM segment with the relatively short luminal segment and a large C-terminal cytosolic domain. Dpm1: A tail-anchor protein, having the tail-anchor (TA) membrane targeting sequence at the C-terminus, whose membrane integration is mediated by the Get3 machinery. Emp47: A protein whose translocation is initiated by the cleavable signal sequence (SS) to generate the large luminal domain, but halted by the TM segment near the C-terminus. Pho8: A protein with a large luminal domain, including the ribosome-engaging C-terminal end, that is translocated by the type II signal-anchor (SA) sequence.