A new player in the starch field

A possible role of a newly discovered ADP-glucose pyrophosphatase (AGPPase) is discussed in the context of starch synthesis. The enzyme hydrolyses ADP-glucose (starch precursor) and may potentially divert the flow of carbon from starch synthase, resulting in a 'futile cycle' when 'coupled' with ADP-glucose pyrophosphorylase. The activity of AGPPase is inversely related to starch yield in sink tissues, and may be prone to inhibition by Pi and certain other products of the starch pathway. The AGPPase likely belongs to a `nudix' family of enzymes that in animal tissues and yeast are known to regulate levels of activated sugars. Some strategies for future research are underlined. (C) 2001 Editions scientifiques et medicales Elsevier SAS.