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Cell. 1990 Sep 21;62(6):1135-41.

Fine-tuning the topology of a polytopic membrane protein: role of positively and negatively charged amino acids.

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Department of Molecular Biology, Karolinska Institute Center for Biotechnology, NOVUM, Huddinge, Sweden.


The effects of positively and negatively charged residues on the membrane topology of a model E. coli protein with two transmembrane segments have been studied. We show that addition or removal of as little as a single positively charged lysine residue in one of two critical regions can be sufficient to reverse the transmembrane topology of the molecule from Nout-Cout to Nin-Cin. Negatively charged residues are much less potent and significantly affect the topology only if present in high numbers. Finally, we provide data to suggest that sec-independent and sec-dependent translocation mechanisms differ in their sensitivity to positively charged amino acids.

[Indexed for MEDLINE]

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