A novel glycoprotein of feline infectious peritonitis coronavirus contains a KDEL-like endoplasmic reticulum retention signal.
A new protein of feline infectious peritonitis coronavirus (FIPV) was discovered in lysates of [35S]cysteine-labeled infected cells. Expression of open reading frame (ORF) 6b of FIPV in recombinant vaccinia virus-infected cells was used to identify it as the 6b protein. Further characterization revealed that it is a novel type of viral glycoprotein whose function is not clear. It is a soluble protein contained in microsomes; its slow export from the cell is caused by the presence of an endoplasmic reticulum (ER) retention signal at the C terminus. This amino acid sequence, KTEL, closely resembles the consensus KDEL signal of soluble resident ER proteins. A mutant 6b protein with the C-terminal sequence KTEV became resistant to digestion by endo-beta-N-acetylglucosaminidase H with a half-time that was reduced threefold. In contrast, a mutant with the sequence KDEL was completely retained in the ER. The FIPV 6b protein is the first example of a viral protein with a functional KDEL-like ER retention signal.
Vennema
H
H
Department of Virology, Faculty of Veterinary Medicine, State University of Utrecht, The Netherlands.
Heijnen
L
L
Rottier
P J
PJ
Horzinek
M C
MC
Spaan
W J
WJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002415:Cats; D002460:Cell Line; D002478:Cells, Cultured; D003001:Cloning, Molecular; D016765:Coronavirus, Feline / Q000235:genetics / Q000502:physiology*; D003545:Cysteine / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000502:physiology*; D005333:Fetus; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D016366:Open Reading Frames; D010957:Plasmids; D011499:Protein Processing, Post-Translational; D015183:Restriction Mapping; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism
D006023:Glycoproteins; D009838:Oligodeoxyribonucleotides; D014764:Viral Proteins; D003545:Cysteine