Stable membrane orientations of small dual-topology membrane proteins

Nir Fluman, Victor Tobiasson, Gunnar von Heijne

Research output: Contribution to journalArticlepeer-review

Abstract

The topologies of alpha-helical membrane proteins are generally thought to be determined during their cotranslational insertion into the membrane. It is typically assumed that membrane topologies remain static after this process has ended. Recent findings, however, question this static view by suggesting that some parts of, or even the whole protein, can reorient in the membrane on a biologically relevant time scale. Here, we focus on antiparallel homo- or heterodimeric small multidrug resistance proteins and examine whether the individual monomers can undergo reversible topological inversion (flip flop) in the membrane until they are trapped in a fixed orientation by dimerization. By perturbing dimerization using various means, we show that the membrane orientation of a monomer is unaffected by the presence or absence of its dimerization partner. Thus, membrane-inserted monomers attain their final orientations independently of dimerization, suggesting that wholesale topological inversion is an unlikely event in vivo.

Original languageEnglish
Pages (from-to)7987-7992
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number30
DOIs
StatePublished - 25 Jul 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General

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