C-type lectins are a family of proteins with an affinity to carbohydrates in the presence of Ca2+. In the genome of Caenorhabditis elegans, almost 300 genes encoding proteins containing C-type lectin-like domains (CTLDs) have been assigned. However, none of their products has ever been shown to have carbohydrate-binding activity In the present study, we selected 6 potential C-type lectin genes and prepared corresponding recombinant proteins. One of them encoded by clec-79 Was found to have sugar-binding activity by using a newly developed glycoconjugate microarray based oil evanescent-field excited fluorescence.. CLEC-79 exhibited affinity to Sugars containing galactose at the non-reducing terminal, especially to the Gal beta 1-3GalNAc structure, in the presence of Ca2+. Combined with structural information of the glycans of C. elegans, these results suggest that CLEC-79 preferentially binds to O-glycans in vivo. (C) 2008 Elsevier Inc. All rights reserved.