Rittenhouse J, Moberly L, O'Donnell M E, Owen N E, Marcus F
J Biol Chem. 1986 Jun 15;261(17):7607-10.
Atrial natriuretic peptides refer to a family of related peptides secreted by atria that appear to have an important role in the control of blood pressure. The structure of these peptides shows the amino acid sequence Arg101-Arg102-Ser103-Ser104, which is a typical recognition sequence (Arg-Arg-X-Ser) for phosphorylation by cyclic AMP-dependent protein kinase. With this background, we tested two synthetic atrial natriuretic peptides (Arg101-Tyr126 and Gly96-Tyr126) as substrates for in vitro phosphorylation by the catalytic subunit of cyclic AMP-dependent protein kinase. The tested atrial natriuretic peptides were found to be substrates for the reaction. Sequence studies demonstrated that the site of phosphorylation was located, as expected, at Ser104. Kinetic studies demonstrate that both atrial natriuretic peptides are excellent substrates for cyclic AMP-dependent protein kinase. In particular, the longer peptide Gly96-Tyr126 exhibited an apparent Km value of about 0.5 microM, to our knowledge the lowest reported Km for a cyclic AMP-dependent protein kinase substrate. Preliminary studies to measure the biological activity of the in vitro phosphorylated atrial peptides indicate that these compounds are more effective than the corresponding dephospho forms in stimulating Na/K/Cl cotransport in cultured vascular smooth muscle cells.
心房利钠肽是指由心房分泌的一族相关肽，它们似乎在血压控制中起重要作用。这些肽的结构显示出氨基酸序列Arg101-Arg102-Ser103-Ser104，这是环磷酸腺苷依赖性蛋白激酶磷酸化的典型识别序列（Arg-Arg-X-Ser）。在此背景下，我们测试了两种合成的心房利钠肽（Arg101-Tyr126和Gly96-Tyr126）作为环磷酸腺苷依赖性蛋白激酶催化亚基体外磷酸化的底物。经测试发现，所检测的心房利钠肽是该反应的底物。序列研究表明，磷酸化位点正如预期的那样位于Ser104。动力学研究表明，两种心房利钠肽都是环磷酸腺苷依赖性蛋白激酶的优良底物。特别是，较长的肽Gly96-Tyr126表现出约0.5微摩尔的表观Km值，据我们所知，这是环磷酸腺苷依赖性蛋白激酶底物中报道的最低Km值。测量体外磷酸化心房肽生物活性的初步研究表明，这些化合物在刺激培养的血管平滑肌细胞中的Na/K/Cl协同转运方面比相应的去磷酸化形式更有效。
