IDENTIFICATION OF THE ATRIAL NATRIURETIC FACTOR-R1C RECEPTOR SUBTYPE (B-CLONE) IN CULTURED RAT AORTIC SMOOTH-MUSCLE CELLS

The present report demonstrates the presence in cultured rat aortic smooth muscle cells of a natriuretic factor receptor subtype with a specificity typical of the ANF-R1C (B-clone) receptor subtype. To prove the existence of this receptor subtype in this cell line we show that pCNP-(82-103) is the most potent activator of the intrinsic guanylate cyclase activity, and that [I-125]pCNP-(82-103) binds to a specific receptor subtype which is insensitive to the ANF-R2 specific ligand, C-ANF. The investigation of its binding characteristics show the rank potency order of the natriuretic factors in competing for pCNP binding to be pCNP > pBNP > rANF. Furthermore it was possible to covalently photolabel this receptor subtype with underivatized ]I-125]pCNP and show that it is composed of a single subunit of 130 kDa with very high specificity for pCNP.