Crystallization and preliminary X-ray analysis of the atrial natriuretic peptide (ANP) receptor extracellular domain complex with ANP: use of ammonium sulfate as the cryosalt

Atrial natriuretic peptide (ANP) plays a major role in blood pressure and volume regulation owing to its natriuretic and vasodilatory activities. The ANP receptor is a single-span transmembrane receptor coupled to its intrinsic guanylyl cyclase activity. The extracellular hormone-binding domain of rat ANP receptor (ANPR) was overexpressed by permanent transfection in CHO cells and purified. ANPR complexed with ANP was crystallized at 301 K by the hanging-drop vapor-diffusion method. The crystals were frozen in 3.4 M ammonium sulfate used as a cryoprotectant. The crystals diffracted to 3.1 Å resolution using synchrotron radiation and belonged to the hexagonal space group P6₁, with unit-cell parameters a = b = 100.3, c = 258.6 Å.