Fig. 3.

Mutations in catalytic domain of LT82 abolish both GTPase-glucosylating and ACh release-blocking activities.A, Protein substrate specificity of glucosylation by LT82 (top panel), recombinant LT82 fragment (amino acids 1–546) containing an intact catalytic domain (middle panel; LT82 NH2) or a D to A exchange at positions 286 and 288 (bottom panel;LT82 NH2 mutant). Recombinant GTPases (1 μg of each) were incubated with LT or fragments (5 μg/ml) in the presence of UDP-¹⁴C-glucose for 60 min at 37°C. Labeled proteins were analyzed by SDS-PAGE and autoradiography. Position of molecular weight markers is indicated. B, The effect of recombinant fragments on ACh release. Same presentation of the data as in Figure2C. ** denotes significant difference (p < 0.001).