Functional diversity of rhamnogalacturonans I

Rhamnogalacturonans I represent a group of plant cell wall polysaccharides having the most complex organization and variable structure. These polymers, combined in one group due to the presence of a backbone composed of alternating [-> 4)-alpha-d-GalpA-(1 -> 2)-alpha-l-Rhap(1 ->] dimers, can occur in the cell wall both as parts of a pectin complex and by themselves. Types of rhamnogalacturonans I are unique not only for each plant but also for different tissues of the same plants and, in some cases, for different stages of development of the same tissue. Perception of the causes and consequences of this diversity is a sophisticated problem of plant glycobiology. The review summarizes the available information on the correlation of structure, physicochemical properties, and functions of rhamnogalacturonans I.