| Abstract: | Specific, high-affinity receptors for atrial natriuretic factor (ANF) have been identified on membranes from a variety of tissues and cultured cells. By affinity labeling procedures, radioactivity from 125I-labeled ANF was specifically incorporated into three different polypeptides of ca. 120,000, 70,000, and 60,000 daltons, which may represent the binding subunits of ANF receptors. These polypeptides were present in varying amounts in different target tissues. In rat adrenal membranes, the 120,000- and 70,000-dalton peptides were specifically labeled whereas in A10 rat smooth muscle cells, only the 60,000-dalton peptide was labeled. Membranes from rat kidney and rabbit aorta contain all three peptides. Gel filtration chromatography of solubilized receptors suggested that intact ANF receptors are large molecular complexes with apparent molecular masses in the range of 250,000-350,000 daltons. The differential labeling pattern observed with the various tissues suggested that there might be at least two different receptors composed of unique ANF-binding polypeptides. |
