LOCALIZATION AND IDENTIFICATION OF GALACTOSE/N-ACETYLGALACTOSAMINE AND SIALIC ACID-CONTAINING PROTEINS IN CHINESE HAMSTER METAPHASE CHROMOSOMES |
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Authors: | JOHANNA MYLLYHARJU SEPPO NOKKALA |
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Institution: | 1. Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil;2. Departamento de Física, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil;3. Instituto Nacional de Pesquisas da Amazônia-INPA, Manaus, Amazonas, Brazil;4. Department of Biotechnology, Ghent University, 9000 Ghent, Belgium;1. Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil;2. Centro Acadêmico do Agreste, Universidade Federal de Pernambuco, Caruaru, Pernambuco, Brazil;3. Departamento de Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, Juazeiro, Bahia, Brazil;4. Departamento de Histologia e Embriologia, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Brazil |
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Abstract: | Four lectins were used to recognize galactose/N-acetyl-galactosamine (Gal/GalNAc) and sialic acid residues in proteins of Chinese hamster metaphase chromosomes. In situ binding pattern of a fluorescein isothiocyanate-labelled (Gal/GalNAc)-specific lectin Sophora japonica agglutinin (SJA) showed that chromosomal SJA-binding proteins are primarily localized to the helically coiled substructure of chromatids. Numerous SJA-binding proteins were identified in Western blots of chromosomal proteins, their molecular weights ranging from 26 to 200kDa. Another Gal/GalNAc-specific lectin, peanut agglutinin (PNA), with a slightly different sugar binding specificity, did not bind to Chinese hamster metaphase chromosomes, and in Western blots only two chromosomal protein bands were faintly stained. The in situ labelling patterns of two sialic acid-specific lectins, Maackia amurensis (MAA) and Sambucus nigra (SNA) agglutinins, both showed that the helically coiled substructure of chromatids is also enriched in sialylated proteins. In Western blot analysis 11 MAA-binding protein bands with molecular weights ranging from 54 to 215kDa were identified, while SNA only bound to one protein band of 67kDa. MAA and SNA are specific for α (2|ad3)- and α (2|ad6)-linked sialic acid residues, respectively. Thus, it is likely that α (2|ad3)-linked sialic acid residues are more common in chromosomal proteins than α(2|ad6)-linked sialic acid residues. These data suggest that Gal/GalNAc and sialic acid-containing glycoproteins exist in metaphase chromosomes and that these proteins may have a role in the formation of higher order metaphase chromosome structures. |
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Keywords: | glycoproteins metaphase chromosomes lectins galactose N-acetylgalactosamine sialic acid |
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