FIGURE 6.

Schematic drawing of the glycan cycle (fucose cycle). Glycosylation is affected by various factors as described in text, and the pro-form is converted to the mature form of glycoproteins by glycosyltransferases and then localized on the cell surface, such as growth factor receptors by binding to lectins. The similar cycles such as the GlcNAc cycle, sialic acid cycle, etc., will be present. TGFβ-R; TGF-β receptor; GMD, GDP-mannose 4,6-dehydratase; FX, GDP-keto-6-deoxymannose 3,5-epimerase/4-reductase; ER, endoplasmic reticulum.