Proteins from U1 and U2 small nuclear ribonucleoprotein (snRNP) particles, which are common targets of autoantibodies found in some rheumatic diseases, were analysed for the presence of glycans. A glycan detection assay revealed that the U1-specific proteins 68K and A and the U2-specific protein B" are glycosylated. However, none of the Sm proteins, which are common to all the major snRNP particles, showed a detectable level of glycosylation. With the use of specific lectins, an analysis of the particular carbohydrate(s) attached to the U1 snRNP 68K protein demonstrated the presence of at least one N-linked oligosaccharide chain. Lectin detection of galactose, glucose, mannose and N-acetylglucosamine on 68K was confirmed by chemical analysis of the carbohydrates. The glycopeptide nature of these antigens may be important for understanding the role of autoantigens in the pathogenesis of autoimmune disorder.
Tan EMAntinuclear antibodies: diagnostic markers for autoimmune diseases and probes for cell biology. Adv Immunol1989; 44: 93-151.
2.
Steitz JA, Black DL, Gerke V., Parker KAStructure and Function of Major and Minor Small Nuclear Ribonucleoprotein Particles. Berlin: Springer-Verlag , 1988: 115.
3.
Pettersson I. , Wang G., Smith EI et al. The use of immunoblotting and immunoprecipitation of (U) small nuclear ribonucleoproteins in the analysis of sera of patients with mixed connective tissue disease and systemic lupus erythematosus: a cross-sectional longitudinal study. Arthritis Rheum1986; 29: 986-96.
4.
Habets WJ, Hoet M., Bringmann P., Lührmann R., van Venrooij WJ.Autoantibodies to ribonucleoprotein particles containing U2 small nuclear RNA. EMBO J1985; 4:1545-50.
5.
Pettersson I. , Hinterberger T., Mimori E., Gottlieb E., Steitz JAThe structure of mammalian small nuclear ribonucleoproteins . J Biol Chem1984; 259: 5907-14.
6.
Wieslander J. , Mansson O., Kallin E., Gabrielli A., Nowack H., Timpl R.Specificity of human antibodies against Gal-alpha-1-3Gal carbohydrate epitope and distinction from natural antibodies reacting with Gal-alpha-1-2Gal or Gal-alpha-1-4Gal. Glycoconj J1990; 7: 85-100.
7.
Takeda Y., Wang GS, Wang RJ et al. Enzyme-linked immunosorbent assay using isolated (U) small nuclear ribonucleoprotein polypeptides as antigens to investigate the clinical significance of autoantibodies to these polypeptides. Clin Immunol Immunopathol1989; 50: 213-30.
8.
Boak AM, Kincaid LA, Treadwell EL et al. Comparison of various preparations of nuclear antigens by hemagglutination inhibition (HAI). Immunol Commun1984; 13(2): 127-36.
9.
Chen J., Takeda Y., Vanderslice WE et al. Human autoantibody secreted by immortalized lymphocyte cell line against the 68K polypeptide of the U1 small nuclear ribonucleoprotein . Arthritis Rheum1988; 31: 1265-71.
10.
Habets WJ, Hoet MH, de Jong Baw, vander Kemp A., van Venrooij WJMapping of B cell epitopes on small nuclear ribonucleoproteins that react with human autoantibodies as well as with experimentally-induced mouse monoclonal antibodies. J Immunol1989; 143: 2560-6.
11.
Laemmli UKCleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature1970; 227: 680-5.
12.
Haselbeck A. , Hosel W.Description and application of an immunological detection system for analyzing glycoproteins on blots. Glycoconj J1990; 7: 63-74.
13.
Shibuya N., Goldstein IJ, van Damme Ejm, Peumans WJBinding properties of a mannose-specific lectin from the snowdrop (Galanthus nivalis) bulb. J Biol Chem1988; 263: 728-34.
Wang WC, Cummings RDThe immobilized leukoagglutinin from the seeds of Maackia amurensis binds with high affinity to complex-type Asn-linked oligosaccharides containing terminal sialic acid-linked alpha-2,3 to penultimate galactose residues. J Biol Chem1988; 263: 4576-85.
16.
Crowley JF, Goldstein I., Arnarp J., Lonngren J.Carbohydrate binding studies on the lectin from Datura stramonium seeds. Arch Biochem Biophys1985; 231: 524-33.
17.
Goldstein IJ , Hayes CEThe lectins: carbohydrate-binding proteins of plants and animals. Adv Carbohyd ChemBiochem1978; 35: 127.
18.
Paulson JCGlycoproteins: what are the sugar chains for?Trends Biochem Sci1989; 14: 272-6
19.
Hart GW, Haltiwanger RS, Holt GD, Kelly WGGlycosylation in the nucleus and cytoplasm. Ann Rev Biochem1989; 58: 841-74.
20.
Agris PF, Parks R., Bowman L., Guenther RH, Kovacs SA, Pelsue S.Plant DNA topoisomerase I is recognized and inhibited by human Scl-70 sera autoantibodies. Exp Cell Res1990; 189: 276-9.
21.
Coppel RL, Gershwin ME, Sturgess ADCloned autoantigens in the study and diagnosis of autoimmune diseases. Mol Biol Med1989; 6: 27-34.
22.
Kohsaka H., Yamamoto K., Fujii H. et al. Fine epitope mapping of the human SS-B/La protein -identification of a distinct auto-epitope homologous to a viral GAG polyprotein. J Clin Invest1990; 85: 1566-74.
23.
Guldner HH, Netter HJ, Szostecki C., Lakomek HJ, Will H.Epitope mapping with a recombinant human 68-kDa (Ul) ribonucleoprotein antigen reveals heterogeneous autoantibody profiles in human autoimmune sera. J Immunol1988; 141: 469-75.
24.
Spritz RA, Strunk K., Surowy CS, Hoch SO, Barton DE, Francke U.The human Ut-70K snRNP protein: cDNA cloning, chromosomal localization, expression, alternative splicing and RNAbinding. Nucl Acids Res1987; 15: 10373-91.
