FIGURE 7.

Inhibition of GalNAc transfer by peptides CA1–19 and α32–46. Upper panel, the peptide CA1–19 inhibited transfer of GalNAc to GLucα(PLRSKK)CA1–19 with an IC₅₀ of 0.77 μm for β4GalNAc-T3-F and 1.83 μm for β4GalNAc-T4-F. Lower panel, the peptide α32–46 inhibited transfer of GalNAc to GLucα(PLRSKK) with an IC₅₀ of 0.38 μm for β4GalNAc-T3-F and 4.59 μm for β4GalNAc-T4-F. The best fit of the data for inhibition with CA1–19 and α32–46 was obtained using nonlinear transforms and assuming a single binding site. Error bars indicate S.E.