The human interferon-α (IFN-α) family is encoded by 13 different functional genes, and including all cloned sequence variants there are 28 potential IFN-α proteins. To find out which of the described sequences are expressed in normal human leucocytes, we have isolated and partly characterized the components of a highly purified IFN-α preparation produced by Sendai virus-induced human peripheral blood leucocytes. The identification protocol consisted of N-terminal sequencing and mass mapping of the proteins separated by reverse-phase HPLC and/or SDS/PAGE. The highly purified leucocyte IFN-α preparation was found to contain at least nine different IFN-α species: IFN-α1a, IFN-α2b, IFN-α4b, IFN-α7a, IFN-α8b, IFN-α10a, IFN-α14c, IFN-α17b and IFN-α21b. IFN-α1a was the major subtype, comprising approx. 30% of total leucocyte IFN-α. IFN-α14c, the only subtype containing potential N-glycosylation sites, was shown to be glycosylated at Asn-72. Molecular mass determination of the intact proteins by electrospray ionization MS showed that there are no other post-translational modifications in the IFN-α subtypes than the glycosylation of IFN-α2b and IFN-α14c. Only one sequence variant was found for each subtype, suggesting that the other described gene sequences represent allelic variants or mutations that are more rarely found in the general population.
Identification of nine interferon-α subtypes produced by Sendai virus-induced human peripheral blood leucocytes
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A. Tuula NYMAN, Hannele TÖLÖ, Jaakko PARKKINEN, Nisse KALKKINEN; Identification of nine interferon-α subtypes produced by Sendai virus-induced human peripheral blood leucocytes. Biochem J 15 January 1998; 329 (2): 295–302. doi: https://doi.org/10.1042/bj3290295
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