Membrane transport proteins with complete replacement of transmembrane helices with polyalanine sequences remain functional

Xiaoyong Bao, Yongyue Chen, Haeng Lee Sung, Chang Lee Sung, Luis Reuss, Guillermo A. Altenberg

Research output: Contribution to journalArticle

20 Scopus citations


Approximately 25% of all genome coding sequences correspond to membrane proteins, which perform varied and essential functions in cells. Eukaryotic integral membrane proteins are predominantly α-helical proteins that span the membrane several times. The most frequent approach to identifying transmembrane-helix amino acids essential for function is to substitute native residues, one at a time, with Cys or Ala (Cys- and Alascanning mutagenesis). Here, we present a new approach, in which complete transmembrane-helix native sequences are substituted with poly-Ala sequences. We show that the basic functional features of two dissimilar membrane proteins, which function as a channel and a pump, respectively, are maintained when certain individual α-helices are replaced with poly-Ala sequences. This approach ("helix-scanning mutagenesis") allows for rapid identification of helices containing residues essential for function and can be used as a primary helix-screening tool, followed by individual amino acid substitutions when specific helix poly-Ala replacements cause functional changes in the protein.

Original languageEnglish (US)
Pages (from-to)8647-8650
Number of pages4
JournalJournal of Biological Chemistry
Issue number10
StatePublished - Mar 11 2005


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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