Figure 8. Skp1 substrate activity toward Gnt1.

(A) Skp1A was hydroxylated as in Fig. 2 and Hyp-peptides were prepared as in Fig. 4A. Incorporation in the presence of purified DdDp-His₆Gnt1 and UDP-[³H]GlcNAc was assayed as described in Methods. (B) Gnt1 was pretreated with peptides or the non-substrates Skp1A or Skp1A3(P143A) prior to assay as in panel A. (C) Normal and mutant HO-Skp1 samples, left untreated or subjected to denaturing treatments as in Fig. 4, were incubated at 0.31 µM and assayed as above. Data are presented as average values ± SEM.