Figure 8

Vigilin expression level does not alter the protease activity of SPP. (A) The knockdown and over-expression of vigilin did not substantially alter the ability of SPP to cleave the prolactin substrate in the in vitro SPP assay. The positive control used in this study is a purified yeast homolog of SPP that cleaves the prolactin signal peptide substrate, while the negative control is set up without the addition of proteins. Expression level of vigilin was compared to the loading control, GAPDH. Total lysate concentration was adjusted to ensure equal loading of protein samples into the reaction. Data shown are representative blots from three independent experiments. (B) Densitometry analysis of three independent knockdown/overexpression and reactions. Bars represent mean ± s.e.m. The unpaired t-test was performed using Prism (n.s., not significant, p-value > 0.05).