Figure 3.
Three possible roles of the highly glycosylated arabinogalactan proteins (AGPs). (1) A specific phospholipase may cleave the glycosylphosphatidylinositol anchor (GPI) thus releasing AGPs into the cell wall and in the extracellular space. (2) AGPs may serve as storage molecules for Ca2+ and release them in response to different stimuli thus activating Ca-dependent signal cascades. (3) N-acetylglucosamine containing carbohydrate branches may be targets for the action of plant chitinases thus releasing oligosaccharides with signaling or osmotic adjustment functions.