Figure 1.

MUC1 maturation in ldlD cells is rescued by Gal and GalNAc. CHO and ldlD cells expressing human MUC1 were pulse labeled with [³⁵S]Met/Cys for 15 min and chased for 0–120 min. Where indicated, both 100 μM Gal and 1000 μM GalNAc (+G/GN) were included in the starvation, pulse and chase media. MUC1 was immunoprecipitated from cell extracts and subjected to SDS-PAGE on a 3–10% polyacrylamide gradient gel before fluorography of the dried gel. C0 and C60 in each panel show immunoprecipitates from nontransfected control cells, which were labeled and then chased for 0 and 60 min, respectively. M22 (∼250 kDa) and P22 (130 kDa) denote the positions of the mature and propeptide forms of the recombinant MUC1 with 22 tandem repeats, respectively.