Association of the infectious bronchitis virus 3c protein with the virion envelope

Virology. 1991 Dec;185(2):911-7. doi: 10.1016/0042-6822(91)90572-s.


A highly purified radiolabeled preparation of the coronavirus infectious bronchitis virus (IBV) was analyzed, by immunoprecipitation with monospecific antisera, for the presence of a series of small virus proteins recently identified as the products of IBV mRNAs 3 and 5. One of these, 3c, a 12.4K protein encoded by the third open reading frame of the tricistronic mRNA3 was clearly detectable and was found to cofractionate with virion envelope proteins on detergent disruption of virus particles. These results, together with the hydrophobic nature of 3c and its previously demonstrated association with the membranes of infected cells, suggest strongly that 3c represents a new virion envelope protein, which may have counterparts in other coronaviruses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Coronaviridae / chemistry*
  • Coronaviridae / genetics
  • Coronavirus 3C Proteases
  • Cysteine Endopeptidases / chemistry*
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / isolation & purification
  • Electrophoresis, Polyacrylamide Gel
  • Humans
  • Molecular Sequence Data
  • Open Reading Frames / genetics
  • Precipitin Tests
  • RNA, Messenger / genetics
  • RNA, Viral / genetics
  • Viral Envelope Proteins / chemistry*
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / isolation & purification


  • RNA, Messenger
  • RNA, Viral
  • Viral Envelope Proteins
  • Cysteine Endopeptidases
  • 3C-like proteinase, Avian infectious bronchitis virus
  • Coronavirus 3C Proteases