Figure 8.

Mutation of Ser-497 or Thr-500 does not block the desensitization of NPR-A. Human 293 cells were transiently transfected with the indicated NPR-A expression constructs; 48 h later the cells were washed and then incubated in the presence (Desensitized) or absence (Control) of 200 μM ANP for 1 h. Crude membranes were prepared and assayed for guanylyl cyclase activity in the presence of ANP, ATP, and Mg²⁺-GTP (A) or Mn²⁺-GTP and 1% Triton X-100 (B). The vertical bars centered above the columns represent the range of values obtained from two separate determinations, which were determined in duplicate. When the error is <3%, the error bars are not shown.