Your browser doesn't support javascript.
loading
Ligand induced galectin-3 protein self-association.
Lepur, Adriana; Salomonsson, Emma; Nilsson, Ulf J; Leffler, Hakon.
Afiliação
  • Lepur A; Microbiology, Immunology, and Glycobiology (MIG) Section, Department of Laboratory Medicine, Lund University, 223 62 Lund, Sweden. adrianalepur@gmail.com
J Biol Chem ; 287(26): 21751-6, 2012 Jun 22.
Article em En | MEDLINE | ID: mdl-22549776
ABSTRACT
Many functions of galectin-3 entail binding of its carbohydrate recognition site to glycans of a glycoprotein, resulting in cross-linking thought to be mediated by its N-terminal noncarbohydrate-binding domain. Here we studied interaction of galectin-3 with the model glycoprotein asialofetuin (ASF), using a fluorescence anisotropy assay to measure the concentration of free galectin carbohydrate recognition sites in solution. Surprisingly, in the presence of ASF, this remained low even at high galectin-3 concentrations, showing that many more galectin-3 molecules were engaged than expected due to the about nine known glycan-based binding sites per ASF molecule. This suggests that after ASF-induced nucleation, galectin-3 associates with itself by the carbohydrate recognition site binding to another galectin-3 molecule, possibly forming oligomers. We named this type-C self-association to distinguish it from the previously proposed models (type-N) where galectin-3 molecules bind to each other through the N-terminal domain, and all carbohydrate recognition sites are available for binding glycans. Both types of self-association can result in precipitates, as measured here by turbidimetry and dynamic light scattering. Type-C self-association and precipitation occurred even with a galectin-3 mutant (R186S) that bound poorly to ASF but required much higher concentration (∼50 µM) as compared with wild type (∼1 µM). ASF also induced weaker type-C self-association of galectin-3 lacking its N-terminal domains, but as expected, no precipitation. Neither a monovalent nor a divalent N-acetyl-D-lactosamine-containing glycan induced type-C self-association, even if the latter gave precipitates with high concentrations of galectin-3 (>∼50 µM) in agreement with published results and perhaps due to type-N self-association.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Galectina 3 Tipo de estudo: Risk_factors_studies Limite: Humans Idioma: En Revista: J Biol Chem Ano de publicação: 2012 Tipo de documento: Article País de afiliação: Suécia

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Galectina 3 Tipo de estudo: Risk_factors_studies Limite: Humans Idioma: En Revista: J Biol Chem Ano de publicação: 2012 Tipo de documento: Article País de afiliação: Suécia