Ekdahl K N, Ekman P
Biochim Biophys Acta. 1987 Jul 29;929(3):318-26. doi: 10.1016/0167-4889(87)90259-x.
The effects of epinephrine, glucagon and insulin on the activity and degree of phosphorylation of fructose-1,6-bisphosphatase in isolated hepatocytes maintained in cell culture for 24 h were investigated. Epinephrine caused a rapid decrease in the apparent Km monitored as the activity ratio between the activity at 12.5 and 83 microM fructose-1,6-bisphosphate, reaching a maximum after 5 min. Glucagon caused a slower and less pronounced activation, and insulin caused an equally slow increase in Km. The effect of epinephrine and glucagon was completely reciprocated by insulin and the action of insulin was totally erased by the other two. Glucagon stimulated the incorporation of [32P]phosphate into fructose-1,6-bisphosphatase from about 2.5 to 4.2 mol/mol enzyme and epinephrine to 3.5 mol/mol. The effect of the two hormones acting together was cumulative. Insulin brought about a decrease in the degree of phosphorylation to 2.0 mol/mol. The effect of epinephrine was shown to be caused by the beta-receptors, since it was completely blocked by propanolol (a beta-antagonist) and remained unaffected by the presence of phentolamine (an alpha-antagonist).
研究了肾上腺素、胰高血糖素和胰岛素对在细胞培养中维持24小时的离体肝细胞中果糖-1,6-二磷酸酶活性及磷酸化程度的影响。以12.5和83微摩尔果糖-1,6-二磷酸时的活性比作为表观Km进行监测，肾上腺素导致其迅速下降，5分钟后达到最大值。胰高血糖素引起的激活较慢且不太明显，胰岛素则使Km同样缓慢增加。肾上腺素和胰高血糖素的作用完全被胰岛素逆转，而胰岛素的作用则被另外两种物质完全消除。胰高血糖素刺激[32P]磷酸掺入果糖-1,6-二磷酸酶的量从约2.5摩尔/摩尔酶增加到4.2摩尔/摩尔，肾上腺素使其增加到3.5摩尔/摩尔。两种激素共同作用的效果是累积的。胰岛素使磷酸化程度降至2.0摩尔/摩尔。肾上腺素的作用被证明是由β受体引起的，因为它被普萘洛尔（一种β拮抗剂）完全阻断，且不受酚妥拉明（一种α拮抗剂）的影响。
