The rate of glycogenin (Gn) autoglucosylation is dependent on the glucosylation state of Gn prior to incubation with UDPG and it reaches a plateau when the bound-oligosaccharide acquires 8-11 glucose units. The rate of transglucosylation is, under standardized conditions, proportional to the concentration of active Gn and expressed as units of activity has been used to measure the Gn content of different tissues (Carrizo, M.E., et al., 1997, Biochem. Biophys. Res. Commun., 240, 142-145). Having Gn preparations isolated from proteoglycogen by digestion with different amylolytic enzymes we estimated their relative glucosylation states from the autoglucosylation/transglucosylation index (ATI), defined as the auto(14C)glucosylation from UDP-14C-glucose measured at the plateau, per unit of DBM-transglucosylating active enzyme. ATI was also used to determine the relative content of autoglucosylating active Gn of different recombinant Gn preparations. This required prior exhaustive amylolysis of Gn. Taking the ATI value for native glycogenin (coming from amylolyzed proteoglycogen) as 100% (all the Gn autoglucosilable), the ATI values obtained for three recombinant glycogenin preparations were 100%, 66% and 28%, indicating that the proportion of transglucosylating active glycogenin that was inactive for autoglucosylation were, 0%, 34% and 72%, respectively. This result is discussed in terms of possible factors affecting only the acceptor capacity of Gn.