Photoaffinity labeling of ANF receptor in cultured brain neurones

A monoiodo derivative of rat atrial natriuretic factor (rANF) was shown to specifically bind to rat brain neurones in culture with low binding site capacity (10-20 fmoles per mg of protein) and high affinity (Kd = 50-100 pM). Several analogs of both rat and human ANF competed with 125I-rANF. No change in the number of binding sites was detected upon morphological differentiation of neurones in vitro. Finally a photoreactive derivative of 125I-rANF was prepared and photoaffinity labeling experiments carried out on cultured neurones. After reduction of disulfide bridges, a single band of Mr 60,000 was specifically labeled whereas without reduction, two labeled components of Mr 60,000 and 117,000 were detected.