Fig. 5.

Secretion of human interferon Hy3 by protease-deficient strains. (a) Western blot analysis of recombinant Hy3 present in SCM derived from strain GG799 (wt) (± an expression vector) and each protease mutant. (b, c) Analysis of Hy3 secreted by the Kluyveromyces lactisΔyps1 mutant grown to high cell density in a bioreactor. Hy3 secreted after 22.5 and 40.5 h of fermentation was visualized by SDS-PAGE separation of SCM and either Coomassie blue staining (b) or Western blotting (c). SCM from GG799 cells not expressing Hy3 was analyzed as a negative control. In all panels, arrows indicate intact Hy3 protein and M represents a molecular weight marker. In (a) and (c), the asterisk denotes a proteolytic product of Hy3.