Arabinogalactan-proteins are distributed throughout the plant kingdom and are present in leaves, stems, roots, floral parts, and seeds. At the subcellular level, AGPs are localized on the plasma membrane, in the cell wall, in secretory and endocytotic pathway organelles, in stylar and root secretions and in the medium of cultured cells. The widespread distribution of AGPs indicates that they perform important functions. An expansion of knowledge regarding AGPs has been initiated and sustained through new experimental approaches, including the development of monoclonal antibody probes and...

Carbohydrate as the primary product of photosynthesis has a vital role in the maintenance of life on this planet. Until relatively recently, interest in complex carbohydrates focussed on their structural role in the extracellular matrix/ cell wall of animal, plant, and microbial cells and on their role as energy sources (e.g., starch and glycogen) and struc- tural components (e.g., cellulose) in natural products. There was, however, indirect evidence that carbohydrates could play an informational role; this evidence was from the find- ing last century that plant lectins caused specific...