Title : Identification of nine interferon-alpha subtypes produced by Sendai virus-induced human peripheral blood leucocytes
Abstract :
- The human interferon-alpha ( IFN-alpha ) family is encoded by 13 different functional genes, and including all cloned sequence variants there are 28 potential IFN-alpha 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-alpha 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-alpha preparation was found to contain at least nine different IFN-alpha species: IFN-alpha1a, IFN-alpha2b, IFN-alpha4b, IFN-alpha7a, IFN-alpha8b, IFN-alpha10a, IFN-alpha14c, IFN-alpha17b and IFN-alpha21b
- IFN-alpha1a was the major subtype, comprising approx
- 30% of total leucocyte IFN-alpha
- IFN-alpha14c, 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-alpha subtypes than the glycosylation of IFN-alpha2b and IFN-alpha14c
- 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