Ligand induced galectin-3 self-association.

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Ligand induced galectin-3 self-association. / Lepur, Adriana; Salomonsson, Emma; Nilsson, Ulf J; Leffler, Hakon.

In: Journal of Biological Chemistry, Vol. 287, No. 26, 2012, p. 21751-21756.

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Lepur, A, Salomonsson, E, Nilsson, UJ & Leffler, H 2012, 'Ligand induced galectin-3 self-association.', Journal of Biological Chemistry, vol. 287, no. 26, pp. 21751-21756. https://doi.org/10.1074/jbc.C112.358002

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Lepur, Adriana ; Salomonsson, Emma ; Nilsson, Ulf J ; Leffler, Hakon. / Ligand induced galectin-3 self-association. In: Journal of Biological Chemistry. 2012 ; Vol. 287, No. 26. pp. 21751-21756.

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TY - JOUR

T1 - Ligand induced galectin-3 self-association.

AU - Lepur, Adriana

AU - Salomonsson, Emma

AU - Nilsson, Ulf J

AU - Leffler, Hakon

PY - 2012

Y1 - 2012

N2 - 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 non-carbohydrate-binding domain. Here we studied interaction of galectin-3 with the model glycoprotein asialofetuin (ASF), using a fluorescence anisotropy (FA) 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 9 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 turbidometry 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 (~50μM) compared to wild type (~1μM). ASF also induced weaker type-C self-association of galectin-3 lacking its N-terminal part, but, as expected, no precipitation. Neither a monovalent or divalent LacNAc containing glycan induced type-C self-association, even if the latter gave precipitates with high concentrations of galectin-3 (> ~50μM) in agreement with published results, and perhaps due to type-N self-association.

AB - 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 non-carbohydrate-binding domain. Here we studied interaction of galectin-3 with the model glycoprotein asialofetuin (ASF), using a fluorescence anisotropy (FA) 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 9 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 turbidometry 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 (~50μM) compared to wild type (~1μM). ASF also induced weaker type-C self-association of galectin-3 lacking its N-terminal part, but, as expected, no precipitation. Neither a monovalent or divalent LacNAc containing glycan induced type-C self-association, even if the latter gave precipitates with high concentrations of galectin-3 (> ~50μM) in agreement with published results, and perhaps due to type-N self-association.

U2 - 10.1074/jbc.C112.358002

DO - 10.1074/jbc.C112.358002

M3 - Article

C2 - 22549776

VL - 287

SP - 21751

EP - 21756

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 1083-351X

IS - 26

ER -