Severe acute respiratory syndrome coronavirus Orf3a protein interacts with caveolin

J Gen Virol. 2007 Nov;88(Pt 11):3067-3077. doi: 10.1099/vir.0.82856-0.


The orf3a (also called X1 or U274) gene is the largest unique open reading frame in the severe acute respiratory syndrome coronavirus genome and has been proposed to encode a protein with three transmembrane domains and a large cytoplasmic domain. Recent work has suggested that the 3a protein may play a structural role in the viral life cycle, although the mechanisms for this remain uncharacterized. Here, the expression of the 3a protein in various in vitro systems is shown, it has been localized to the Golgi region and its membrane topology in transfected cells has been confirmed. Three potential caveolin-1-binding sites were reported to be present in the 3a protein. By using various biochemical, biophysical and genetic techniques, interaction of the 3a protein with caveolin-1 is demonstrated. Any one of the potential sites in the 3a protein was sufficient for this interaction. These results are discussed with respect to the possible roles of the 3a protein in the viral life cycle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Caveolin 1 / metabolism*
  • Cell Line
  • Cricetinae
  • Dogs
  • Golgi Apparatus / chemistry
  • Humans
  • Microscopy, Fluorescence
  • Molecular Sequence Data
  • Protein Binding
  • Protein Interaction Mapping
  • Severe acute respiratory syndrome-related coronavirus / metabolism*
  • Two-Hybrid System Techniques
  • Viral Structural Proteins / metabolism*


  • Caveolin 1
  • ORF3A protein, SARS coronavirus
  • Viral Structural Proteins