FIG. 7.

PKA negatively regulates cAMP production in C. neoformans. The wild-type, pka1, pka1+PKA1, and pkr1 strains were starved for glucose by growth in YPD medium to stationary phase. Then, 2% glucose was added and, at the indicated times, cells were harvested and crude extracts were prepared. cAMP levels in the extracts were then assessed by enzyme immunoassay. The values shown are the average of triplicate measurements with the standard error of the mean depicted as error bars. The scale of the data shown in panel A has been expanded in panel B to illustrate the levels of cAMP present in the wild type (WT) and in the pkr1 mutant and pka1+PKA1 reconstituted strains.