Regulation of guanylate cyclase by ATP and dithiothreitol in rat lung membrane: involvement of an insensitive and a sensitive state to ATP/dithiothreitol-stimulation.
ATP/dithiothreitol (DTT)-stimulated guanylate cyclase (GC) in lung membrane was stimulated 18-fold by ATP and DTT, and both its activity and atrial natriuretic peptide (ANP)-stimulated GC activity were observed to be additive. ATP/DTT-stimulated GC was solubilized by octyl glucoside (OG) to examine the mechanism of ATP/DTT-stimulation. GC in OG-extracts was stimulated maximally 2.5-fold by both ATP, ATPgammaS or AMPPNP, and DTT. Preincubation of OG-extracts at 10 degrees C with AMPPNP and DTT (1st-preincubation) converted GC to an insensitive state to stimulation by both ATP and DTT, and this conversion was partly inhibited by a protein phosphatase-1 inhibitor (10-1,000 nM okadaic acid). On the other hand, ANP-stimulated GC was not converted to an insensitive state to ANP/ATP-stimulation by the 1st-preincubation. Subsequent preincubation of OG-extracts at 10 degrees C with both DTT and, ATP or ATPgammaS but not AMPPNP converted GC to a state sensitive to ATP/DTT-stimulation, and this conversion was partly inhibited by inhibitors of Ca2+/calmodulin-dependent protein kinase II (KN-62 and KN-93). In contrast, the preincubation with KN-62 and KN-93 had no effect on ANP-stimulated GC activity. The results suggested that phosphorylation was involved in the regulation of ATP/DTT-stimulated GC sensitivity to ATP/DTT-stimulation and that ATP/DTT-stimulated GC activity was likely to be a different type from ANP-stimulated GC activity.
Luo
Shiwen
S
Department of Pharmacology, Faculty of Medicine, Saga Medical School, Japan.
Takano
Masako
M
Asakawa
Takeo
T
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002847:Chromatography, Agarose; D004229:Dithiothreitol / Q000494:pharmacology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000378:metabolism*; D066298:In Vitro Techniques; D008168:Lung / Q000201:enzymology*; D008297:Male; D008566:Membranes; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors; D054645:Protein Phosphatase 1; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility
D004791:Enzyme Inhibitors; D047428:Protein Kinase Inhibitors; D000255:Adenosine Triphosphate; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D006162:Guanylate Cyclase; D004229:Dithiothreitol