GLYCOPROTEINS WITH N-ACETYLGLUCOSAMINE AND MANNOSE RESIDUES IN CHINESE-HAMSTER METAPHASE CHROMOSOMES

Distribution of glycosylated proteins in Chinese hamster metaphase chr omosomes was studied with fluorescein isothiocyanate conjugated lectin s. Three substructural domains with distinct glycoprotein compositions were identified. In situ binding of the lectins Wheat germ agglutinin (WGA) and Datum stramonium agglutinin (DSA) showed that chromosomal p roteins containing N-acetylglucosamine residues preferentially localiz e to the surface domain and the helically coiled substructure of chrom atids. In Western blots, digoxigenin conjugated WGA and DSA bound to s everal chromosomal proteins with molecular weight ranges of 45-220 kD and 66-220 kD, respectively. Binding of Galanthus nivalis agglutinin r evealed that mannosylated chromosomal proteins are enriched at the sur face and G/Q band domains, and their molecular weights range from 97 t o 200 kD. The carbohydrate side chain structure of these mannosylated proteins must be quite specific, as after binding of another mannose-s pecific lectin, Concanavalin A, only a faint fluorescence was observed in metaphase chromosomes and only one protein band of 185 kD was weak ly stained in Western blots. These data suggest that chromosomal glyco proteins containing N-acetylglucosamine and mannose residues play a ro le in the higher order structural organization of metaphase chromosome s.