Figure 12-50. The insertion of the multipass membrane protein rhodopsin into the ER membrane.

Figure 12-50The insertion of the multipass membrane protein rhodopsin into the ER membrane

Rhodopsin is the light-sensitive protein in rod photoreceptor cells in the mammalian retina (discussed in Chapter 15). (A) A hydrophobicity plot identifies seven short hydrophobic regions in rhodopsin. (B) The most N-terminal region serves as a start-transfer sequence that causes the preceding N-terminal portion of the protein to be passed across the ER membrane. Subsequent hydrophobic sequences function in alternation as start-transfer and stop-transfer sequences. (C) The final integrated rhodopsin has its N-terminus located in the ER lumen and its C-terminus located in the cytosol. The blue hexagons represent covalently attached oligosaccharides. Arrows indicate the parts of the protein that are inserted into the translocator.

From: The Endoplasmic Reticulum

Cover of Molecular Biology of the Cell
Molecular Biology of the Cell. 4th edition.
Alberts B, Johnson A, Lewis J, et al.
New York: Garland Science; 2002.
Copyright © 2002, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter; Copyright © 1983, 1989, 1994, Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson .

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