Presence of an intermediate synthase form during the conversion of glycogen synthase D into synthase I in rat liver extract.

When synthase D was converted into synthase I in a liver extract, it progressed through a synthase form with activity characteristics that could not be explained by a mixture of the original synthase D and the final product, synthase I. This form was distinguished by an affinity for UDP-glucose, in the absence of glucose 6-phosphate, which was intermediate between those of the two known forms.