Swa

Signal sequence

Figure 18.10. Schematic representation of two way of the insertion of the nascent polypeptide chain into the translocation channel.

A: When the N-terminus of the nascent polypeptide chains is positively charged, it remains on the cytoplasmic side of the endoplasmic reticulum membrane, the signal sequence is anchored in the membrane (until it is cut off by signal peptidase), and the growing polypeptide chain forms a loop protruding through the channel into the intramembrane lumen.

B: In the case of the negatively charged N-terminus, it goes through the channel and faces the lumen, the signal sequence is anchored in the membrane, and thus the polypeptide chain spans the membrane once.

Signal sequence

Figure 18.10. Schematic representation of two way of the insertion of the nascent polypeptide chain into the translocation channel.

A: When the N-terminus of the nascent polypeptide chains is positively charged, it remains on the cytoplasmic side of the endoplasmic reticulum membrane, the signal sequence is anchored in the membrane (until it is cut off by signal peptidase), and the growing polypeptide chain forms a loop protruding through the channel into the intramembrane lumen.

B: In the case of the negatively charged N-terminus, it goes through the channel and faces the lumen, the signal sequence is anchored in the membrane, and thus the polypeptide chain spans the membrane once.

A Uncleavable signal peptide (USP)

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