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Updated: Feb 27, 2026

Determining Membrane Protein Topology Using Fluorescence Protease Protection FPP
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Determining Membrane Protein Topology Using Fluorescence Protease Protection FPP

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Probing Inner Membrane Protein Topology by Proteolysis

Maxence S Vincent1, Eric Cascales2

  • 1Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM, UMR 7255), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Université-Centre National de la Recherche Scientifique (CNRS), 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 20, France.

Methods in Molecular Biology (Clifton, N.J.)
|July 2, 2017
PubMed

Inner membrane proteins are inserted into the membrane via α-helices. These helices do not only constitute membrane anchors but may mediate specific interactions with membrane protein partners or participate in energetic processes. The number, location, and orientation of these helices is referred to as topology. Bitopic membrane proteins that consist of a single membrane-embedded domain connecting two soluble domains are distinguished from polytopic ones that consist of multiple membrane-spanning helices connected by extramembrane domains. Defining inner membrane protein topology could be achieved by different methods. Here we describe a protease accessibility assay that makes it possible to define topology based on digestion profiles.

Keywords:
BitopicCarboxypeptidase YInner membraneInsertionMembrane proteinPolytopicProteaseProteinase KProteolysisTopologyTransmembrane segment

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