Atrial natriuretic peptide (ANP) is a polypeptide hormone whose effects include the induction of diuresis, natriuresis and vasorelaxation. One of the earliest events following binding of ANP to receptors on target cells is an increase in cyclic GMP concentration, indicating that this nucleotide might act as a mediator of the physiological effects of the hormone. Guanylate cyclase exists in at least two different molecular forms: a soluble haem-containing enzyme consisting of two subunits and a non-haem-containing transmembrane protein having a single subunit. It is the membrane form of guanylate cyclase that is activated following binding of ANP to target cells. We report here the isolation, sequence and expression of a complementary DNA clone encoding the membrane form of guanylate cyclase from rat brain. Transfection of this cDNA into cultured mammalian cells results in expression of guanylate cyclase activity and ANP-binding activity. The ANP receptor/guanylate cyclase represents a new class of mammalian cell-surface receptors which contain an extracellular ligand-binding domain and an intracellular guanylate cyclase catalytic domain.