The be1 and be2 genes code for starch branching enzymes which
catalyse the splitting of alpha-1,4-glucans and the subsequent
formation of alpha-1,6-glycosidic bonds between glucan chains
during amylopectin synthesis.
The isozymes BE1 and BE2 differ with regard to their amino acid
sequences, their expression patter (BE1 is expressed mainly in
potato tubers, BE2 mainly in leaves) and their specificity (e.g.
size of the transferred carbohydrate chains).