Remaury A, Missy K, Parini A
INSERM U388 Pharmacologie Moléculaire et Physiopathologie Rénale, Institut Louis Bugnard, CHU Rangeuil, Toulouse, France.
J Auton Nerv Syst. 1998 Oct 15;72(2-3):111-7. doi: 10.1016/s0165-1838(98)00095-2.
Several studies have shown that I2 imidazoline binding sites are localized on monoamine oxidases. Recent results obtained after solubilization of rat brain membranes and analysis by size-exclusion chromatography suggested the existence of additional I2 imidazoline binding sites located on proteins distinct from monoamine oxidases. In order to define whether such binding sites are expressed in human and rabbit liver, we solubilized I2 imidazoline binding sites and monoamine oxidases and compared their elution profile by size-exclusion chromatography. I2 binding sites were labeled using [3H]idazoxan. Monoamine oxidases were identified by the measure of [14C]tyramine oxidation and Western blot analysis using an anti-MAO-A/MAO-B polyclonal antiserum. After solubilization of rabbit or human liver using 1% digitonin, 90% of [3H]idazoxan binding eluted in a major peak corresponding to a Mr of approximately 175000 Da. A minor peak, (Mr approximately equal to 100000 Da) representing 10% of the recovered [3H]idazoxan binding, was also observed. [14C]tyramine oxidation as well as immunoreactive bands corresponding to MAOs were exclusively detected in fractions containing [3H]idazoxan binding. These results show that solubilized I2 imidazoline binding sites distinct from monoamine oxidases are not detectable in rabbit and human liver.
多项研究表明，I2咪唑啉结合位点定位于单胺氧化酶上。近期，在对大鼠脑膜进行增溶并通过尺寸排阻色谱法分析后获得的结果表明，存在位于不同于单胺氧化酶的蛋白质上的额外I2咪唑啉结合位点。为了确定此类结合位点是否在人和兔肝脏中表达，我们增溶了I2咪唑啉结合位点和单胺氧化酶，并通过尺寸排阻色谱法比较了它们的洗脱图谱。使用[3H]伊达唑胺标记I2结合位点。通过测量[14C]酪胺氧化以及使用抗MAO - A/MAO - B多克隆抗血清进行蛋白质免疫印迹分析来鉴定单胺氧化酶。使用1%洋地黄皂苷增溶兔或人肝脏后，90%的[3H]伊达唑胺结合在一个主峰中洗脱，该主峰对应的分子量约为175000道尔顿。还观察到一个小峰（分子量约等于100000道尔顿），占回收的[3H]伊达唑胺结合的10%。仅在含有[3H]伊达唑胺结合的级分中检测到[14C]酪胺氧化以及与单胺氧化酶相对应的免疫反应条带。这些结果表明，在兔和人肝脏中无法检测到与单胺氧化酶不同的增溶I2咪唑啉结合位点。
