<figcaption> Credit: Reprinted by permission of Macmillian Publishers, LTD.</figcaption>
Credit: Reprinted by permission of Macmillian Publishers, LTD.

The paper:

T. Hessa et al., ?Recognition of transmembrane helices by the endoplasmic reticulum translocon,? Nature, 433:377?81, 2005. (Cited in 88 papers)

The finding:

Gunnar von Heijne at Stockholm University and colleagues systematically altered the sequence of a transmembrane helix segment to understand how the translocon protein complex determines the segment?s placement in a lipid membrane. ?We figured out how to speak to the translocon, and we?re learning what its code is for inserting transmembrane proteins,? says co-author Stephen White from the University of California, Irvine.

The surprise:

It was easy to imagine that a peptide?s interaction with the translocon determined a segment?s location, says von Heijne. But this paper provided evidence that the protein?s interactions with the lipid bilayer are directing the translocon.

The follow-up:

Von Heijne has tested several hundred additional polypeptides in various systems, such as Escherichia coli...

The numbers:
Free energy range Peptides Favored position
<0 kcal/mol Isoleucine-Valine Hydrocarbon core
-0 kcal/mol Cysteine-Alanine Interfacial region
>0 kcal/mol Charged and polar residues Aqueous layer

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