Type I Interferon Signaling Is Decoupled from Specific Receptor Orientation through Lenient Requirements of the Transmembrane Domain

J Biol Chem. 2016 Feb 12;291(7):3371-84. doi: 10.1074/jbc.M115.686071. Epub 2015 Dec 17.


Type I interferons serve as the first line of defense against pathogen invasion. Binding of IFNs to its receptors, IFNAR1 and IFNAR2, is leading to activation of the IFN response. To determine whether structural perturbations observed during binding are propagated to the cytoplasmic domain, multiple mutations were introduced into the transmembrane helix and its surroundings. Insertion of one to five alanine residues near either the N or C terminus of the transmembrane domain (TMD) likely promotes a rotation of 100° and a translation of 1.5 Å per added residue. Surprisingly, the added alanines had little effect on the binding affinity of IFN to the cell surface receptors, STAT phosphorylation, or gene induction. Similarly, substitution of the juxtamembrane residues of the TMD with alanines, or replacement of the TMD of IFNAR1 with that of IFNAR2, did not affect IFN binding or activity. Finally, only the addition of 10 serine residues (but not 2 or 4) between the extracellular domain of IFNAR1 and the TMD had some effect on signaling. Bioinformatic analysis shows a correlation between high sequence conservation of TMDs of cytokine receptors and the ability to transmit structural signals. Sequence conservation near the TMD of IFNAR1 is low, suggesting limited functional importance for this region. Our results suggest that IFN binding to the extracellular domains of IFNAR1 and IFNAR2 promotes proximity between the intracellular domains and that differential signaling is a function of duration of activation and affinity of binding rather than specific conformational changes transmitted from the outside to the inside of the cell.

Keywords: cell signaling; cytokine receptor; interferon; mutagenesis; protein-protein interaction; transmembrane domain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Line
  • Computational Biology
  • Conserved Sequence
  • Gene Knockout Techniques
  • Humans
  • Interferon-alpha / metabolism*
  • Kinetics
  • Models, Molecular*
  • Mutagenesis, Insertional
  • Mutant Proteins / agonists
  • Mutant Proteins / chemistry
  • Mutant Proteins / metabolism
  • Peptide Fragments / agonists
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Protein Conformation
  • Protein Interaction Domains and Motifs
  • Protein Structure, Tertiary
  • Receptor, Interferon alpha-beta / agonists*
  • Receptor, Interferon alpha-beta / chemistry
  • Receptor, Interferon alpha-beta / genetics
  • Receptor, Interferon alpha-beta / metabolism
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Signal Transduction*


  • IFNA2 protein, human
  • IFNAR1 protein, human
  • IFNAR2 protein, human
  • Interferon-alpha
  • Mutant Proteins
  • Peptide Fragments
  • Recombinant Fusion Proteins
  • Recombinant Proteins
  • Receptor, Interferon alpha-beta

Associated data

  • PDB/3SE3
  • PDB/3WCY