Apolar surface area determines the efficiency of translocon-mediated membrane-protein integration into the endoplasmic reticulum.

The article presents a study which evaluates the effectivity of translocon-mediated insertion model hydrophobic segments carrying nonproteimogenic amino acids into the endoplasmic reticulum (ER) membrane. The study reveals that the contribution of amino acid to the apparent free energy of membrane insertion is immediately proportional to the accessible nonpolar surface field of its side chain. It shows that long alkyl side chains tend to divide into the center of the membrane.