Requirement of divalent galactoside-binding activity of ecalectin/galectin-9 for eosinophil chemoattraction

Nobuko Matsushita, Nozomu Nishi, Masako Seki, Ryoji Matsumoto, Ichiro Kuwabara, Fu-Tong Liu, Yuiro Hata, Takanori Nakamura, Mitsuomi Hirashima

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121 Scopus citations


We have previously isolated and cloned a novel eosinophil chemoattractant (ECA) from a human T-cell-derived expression library. This ECA, termed ecalectin, is a variant of human galectin-9, a member of a β- galactoside binding animal lectin family, which contains two conserved carbohydrate recognition domains (CRDs). In the present study, we addressed whether carbohydrate binding activity is required for the ECA activity of ecalectin and whether both CRDs are essential for this activity. Recombinant full-length wild-type ecalectin (ecalectin-WT) and N-terminal and C-terminal CRD (ecalectin-NT and -CT, respectively) were generated. All of these recombinant proteins exhibited affinity for lactose, a property shared by galectins, but ecalectin-WT exhibited substantially higher hemagglutination activities than ecalectin-NT and -CT. Furthermore, ecalectin-WT showed over 100-fold higher ECA activity than ecalectin-NT and -CT; combination of recombinant domain fragments did not reconstitute the ECA and hemagglutination activities of the full-length protein. ECA activity of ecalectin-WT was inhibited by lactose in a dose-dependent manner. Site- directed mutation of positions Arg55 of ecalectin-NT and Arg239 of ecalectin-CT to an aspartic acid residue resulted in the loss of both lactose-binding and ECA activities. We conclude that divalent galactoside- binding activity is required for eosinophil chemoattraction by ecalectin.

Original languageEnglish (US)
Pages (from-to)8355-8360
Number of pages6
JournalJournal of Biological Chemistry
Issue number12
StatePublished - Mar 24 2000

ASJC Scopus subject areas

  • Biochemistry


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