Figure 4.

ATP and AMPPNP equivalently activate NPR-A-6E but not the wild-type receptor. Human 293 cells were transiently transfected with either wild-type NPR-A or NPR-A-6E expression constructs; 48 h later, crude membranes were prepared, and guanylyl cyclase activities were determined in the presence of 1 μM ANP and 1 mM adenine nucleotide (AMPPNP or ATP) and in the presence or absence of 1 μM microcystin (MC) for 5 min at 37°C. The vertical bars centered above the columns represent the range of values obtained from two separate determinations, which were determined in duplicate.