Figure 5. Replacement of the BiP cysteine with aspartic acid, phenylalanine, tyrosine, or tryptophan results in decreased BiP function.
(A) CSY214 containing the plasmids pCS681, pCS802, pCS687, pCS688, pCS750 or empty vector were spotted onto SMM plates with or without 5-fluoroorotic acid (5-FOA) and incubated for 2 d at 30°C. (B) CSY289, 290, 368, 292, and 293 were spotted onto YPD plates and incubated at 24°, 30°, and 37°C. (C) Strains from B were cultured at 24°C to log-phase in YPD and shifted to 37°C for 90 min prior to harvest. Accumulation of unprocessed untranslocated forms of the proteins Kar2, PDI, and Gas1 were detected by western blotting. (D) Strains from B containing an UPRE-lacZ reporter plasmid (pJC8) were cultured in SMM-ura at 24°C to log-phase and shifted to 37°C (with or without 2 mM DTT) for 90 min prior to harvest. Samples were assayed for beta–galactosidase activity. Three independent transformants of each strain were grown and assayed in duplicate. Data represent the mean of averaged values for the three transformants ± SD. (E–G) ATP hydrolysis was assessed by determining the fraction of [alpha-32P]ATP converted to [alpha-32P]ADP as described in the 'Materials and methods'. Panels F and G show CHP and NEM-treated samples, respectively. Samples without chemical additions in panels F and G were mock treated to match the CHP or NEM-treatment. Data represent the means ± SD of three independent assays.