Figure 4.

A. Neurocalcin δ interacts with the catalytic domain of ANF-RGC. The ANF-RGC fragment aa 788-1029 was expressed in SF-9 cells and purified to homogeneity. The expressed protein was assayed guanylate cyclase activity in the presence of 1 μM Ca²⁺ and indicated concentrations of myristoylated neurocalcin δ. B. Site of neurocalcin δ interaction with ANF-RGC – functional interference. ANF-RGC expressed in COS cells was exposed first to 2 μM myristoylated neurocalcin δ and 1 μM Ca²⁺ than to increasing concentrations (up to 0.5 mM) of peptide covering ANF-RGC sequence aa D⁸⁴⁹-V⁸⁶⁶ or control scrambled peptide, which had the same as D⁸⁴⁹-V⁸⁶⁶ peptide amino acid composition but random sequence. The experiments were done in triplicate and repeated two times. The results presented are mean ± SD of these experiments. The IC₅₀ values were determined graphically.