Palladium-mediated enzyme activation suggests multiphase initiation of glycogenesis.

Biosynthesis of glycogen, the essential glucose (and hence energy) storage molecule in humans, animals and fungi, is initiated by the glycosyltransferase enzyme, glycogenin (GYG). Deficiencies in glycogen formation cause neurodegenerative and metabolic disease, and mouse knockout and inherited human mutations of GYG impair glycogen synthesis. GYG acts as a 'seed core' for the formation of the glycogen particle by catalysing its own stepwise autoglucosylation to form a covalently bound gluco-oligosaccharide chain at initiation site Tyr 195.