, Volume 345, Issue 1, pp 64-70

Comparison of a cloned ANF-sensitive guanylate cyclase (GC-A) with particulate guanylate cyclase from adrenal cortex

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Summary

Recently, an ANF-sensitive guanylate cyclase (GC-A) has been cloned from a rat brain cDNA library. Here we studied the stimulation of cyclic GMP accumulation in response to atrial natriuretic factor (ANF), urodilatin and atriopeptin I (AP-1) in a rat glioma C6 cell line permanently transfected with GC-A as well as GC-A activity in membranes from these C6 cells and in membranes from COS-7 cells that were transiently transfected with GC-A. We also measured binding affinities for these natriuretic peptides in the membrane preparations. These characteristics of GC-A were compared to those of membrane preparations from adrenal cortex of bovine and human origin. The order of potency of stimulation of cyclic GMP accumulation in permanently transfected glioma cells was ANF > urodilatin > AP I; AP I stimulated cyclic GMP accumulation. A similar order of potency was obtained for stimulation of guanylate cyclase activity in membranes from permanently transfected glioma cells as well as from transiently transfected COS-7 cells. In contrast, AP-1 was uneffective to stimulate guanylate cyclase in membrane preparations from adrenal cortex from bovine as well as from human origin. Furthermore, urodilatin was equipotent to ANF in these preparations. Binding affinities were comparable for ANF and urodilatin in membranes from cells transfected with GC-A and in membranes from adrenal cortex of both sources, whereas AP-1 had a weaker affinity in all preparations studied.

These results suggest that GC-A is different from ANF-sensitive guanylate cyclase from bovine and human adrenal cortex and that these cyclases can be distinguished by the ability of AP-1 as well as urodilatin to stimulate guanylate cyclase activity. Since binding characteristics for the studied peptides were comparable, the signal transduction mechanisms rather than binding characteristics may be different in ANF-sensitive guanylate cyclase from adrenal cortex and in GC-A.

Send offprint requests to J. M. Heim at the above address