title: Identification of glycosylation sites in the SU component of the Avian Sarcoma/Leukosis virus Envelope Glycoprotein (Subgroup A) by mass spectrometry.
abstract: We used enzymatic digestion and mass spectrometry to identify the sites of glycosylation on the SU component of the Avian Sarcoma/Leukosis virus (ASLV) Envelope Glycoprotein (Subgroup A). The analysis was done with an SU(A)-rIgG fusion protein that binds the cognate receptor (Tva) specifically. PNGase F removed all the carbohydrate from the SU(A)-rIgG fusion. PNGase F is specific for N-linked carbohydrates; this shows that all the carbohydrate on SU(A) is N-linked. There are 10 modified aspargines in SU(A) (N17, N59, N80, N97, N117, N196, N230, N246, N254, and N330). All conform to the consensus site for N-linked glycosylation NXS/T. There is one potential glycosylation site (N236) that is not modified. Removing most of the carbohydrate from the mature SU(A)-rIgG by PNGase F treatment greatly reduces the ability of the protein to bind Tva, suggesting that carbohydrate may play a direct role in receptor binding.
authors.affiliation: Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy, The Ohio State University Health Sciences Center, Columbus, OH 43210, USA.
authors.forename: Mamuka
authors.initials: M
authors.lastname: Kvaratskhelia
authors.forename: Patrick K
authors.initials: PK
authors.lastname: Clark
authors.forename: Sonja
authors.initials: S
authors.lastname: Hess
authors.forename: Deborah C
authors.initials: DC
authors.lastname: Melder
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Federspiel
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Hughes
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001354:Avian Leukosis Virus / Q000737:chemistry* / Q000378:metabolism; D030161:Avian Proteins; D001358:Avian Sarcoma Viruses / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D037282:Calreticulin / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000737:chemistry; D002460:Cell Line; D002645:Chickens; D006031:Glycosylation; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase / Q000494:pharmacology; D011991:Receptors, Virus / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000378:metabolism; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D037282:Calreticulin; D002241:Carbohydrates; D010446:Peptide Fragments; D011991:Receptors, Virus; C088745:Tva receptor; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase