Structures of the major carbohydrates of natural human interleukin-2.
Purified human interleukin-2 secreted by peripheral blood lymphocytes from healthy donors was found to exist in several forms. These forms were (partially) resolved by reversed-phase high-performance liquid chromatography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Two major polypeptide species (interleukin-2 N1 and N2, 16.5 kDa) were shown to be glycosylated on the basis of [3H]galactose/[3H]glucosamine incorporation and determination of amino sugars after acid hydrolysis. A third component (interleukin-2 M, 14.5 kDa) represents a nonglycosylated form. The amino acid composition and the NH2-terminal sequence of both forms are consistent with the data deduced from the cDNA coding for interleukin-2 after removal of a leader peptide of 20 amino acids. Carbohydrates are O-linked to the IL-2 protein via threonine-3 of the polypeptide chain. The oligosaccharides were released by reductive beta-elimination and were purified by gel filtration and high-performance liquid chromatography. Applying methylation analysis, exoglycosidase digestion and fast atom bombardment mass spectrometry the following major carbohydrate structures were identified: N1, NeuAc(alpha 2-3)Gal(beta 1-3)GalNAc-ol; and N2, NeuAc(alpha 2-3)Gal(beta 1-3)[NeuAc(alpha 2-6)]GalNAc-ol.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D000001:Calcimycin / Q000494:pharmacology; D002241:Carbohydrates / Q000097:blood; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007376:Interleukin-2 / Q000032:analysis*; D008214:Lymphocytes / Q000378:metabolism; D013058:Mass Spectrometry; D008745:Methylation; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000596:Amino Acids; D002241:Carbohydrates; D007376:Interleukin-2; D000001:Calcimycin; D004247:DNA; D013755:Tetradecanoylphorbol Acetate