Glyco-catch method: A lectin affinity technique for glycoproteomics.

Protein glycosylation is a critical issue of post-genome science not only because it is one of the major post-translational modifications but also because it has significant effects on protein properties and functions. The glyco-catch method was recently developed as a novel affinity technique for comprehensive analysis of glycoproteins in the context of glycomics, which is defined as research targeting the whole set of glycans produced in an organism (Hirabayashi J, Kasai K, Trends Glycosci Glycotechnol 2000;12:1-5). This method enables us to identify possible glycoprotein genes as well as glycosylation sites in a systematic manner by combining conventional lectin affinity chromatography and concurrent in silico database searching (Hirabayashi J, Kasai K, J Chromatogr B 2002; 771:67-87). Application of the strategy to a simple organism, Caenorhabditis elegans, has already proved its practical validity (Hirabayashi J, Kaji H, Isobe T, Kasai K, J Biochem (Tokyo) 2002;132:103-114). Accumulation of data on protein glycosylation in a variety of organisms for which entire genome information is available should thus reveal the biological meaning of glycans in complex carbohydrates from a global viewpoint, that is, under the concept of "genome-proteomeglycome." In this article, we briefly review the issues of protein glycosylation and demonstrate the usefulness of the glyco-catch method for identification of complex-type N-glycoproteins of mouse liver that were captured by galectin-1, which is a major galectin in mammals. Future plans for technical improvement and construction of a glycome database are also described.