Carboxypeptidase M in brain and peripheral nerves.
Carboxypeptidase M in brain and peripheral nerves.
复制标题
大脑和周围神经中的羧肽酶 M。
DOI：
10.1111/j.1471-4159.1992.tb10112.x
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发表时间：
1992
影响因子：
4.7
通讯作者：
Erdös,EG
中科院分区：
文献类型：
--
作者：
Nagae,A;Deddish,PA;Becker,RP;Anderson,CH;Abe,M;Tan,F;Skidgel,RA;Erdös,EG
羧肽酶M（CPM）是一种质膜结合酶，在中性pH最适条件下切割C末端碱性氨基酸。我们研究了它在人类，狒狒，狗的大脑和狗的周围神经中的分布。将区域切开，匀浆，离心，并用丹磺酰-Ala-Arg测定活性。胼胝体、锥体束和视束的CPM含量特别丰富，而基底节和皮质的活性较低。通过亚细胞定位、膜附着、底物水解、特异性碱性羧肽酶抑制剂的抑制以及与抗人CPM抗血清的交叉反应的相似性，证明了碱性羧肽酶活性与CPM的同一性。这种抗血清免疫沉淀的平均85%的活动，在人类和狒狒的大脑和狗的大脑中的约66%。CPM与从脑中提取的髓磷脂共纯化。与在胎盘和培养的肾细胞中获得的结果一致，脑中的CPM似乎通过磷脂酰肌醇聚糖锚与膜结合。在周围神经中，犬坐骨神经和迷走神经中的比活度较高（分别为98和149 nmol/h/mg蛋白质）。在免疫组织化学研究中，对大脑中的胶质细胞（似乎是少突胶质细胞或星形胶质细胞）以及坐骨神经和迷走神经中的髓鞘和许旺细胞的外部进行了染色。我们得出结论，在CNS和PNS的某些区域，CPM与髓鞘和髓鞘形成细胞密切相关。北方印迹分析揭示了大脑中存在编码CPM的mRNA，表明这种酶确实是在大脑中合成的。
Carboxypeptidase M (CPM), a plasma membrane‐bound enzyme, cleaves C‐terminal basic amino acids with a neutral pH optimum. We studied its distribution in human, baboon, and dog brain and in dog peripheral nerves. Areas were dissected, homogenized, centrifuged, and assayed for activity with dansyl‐Ala‐Arg. The corpus callosum and the pyramidal and optic tract were especially rich in CPM, whereas basal ganglia and cortex had low activity. The identity of the basic carboxypeptidase activity with CPM was shown by similarities in subcellular localization, membrane attachment, substrate hydrolysis, inhibition by a specific basic carboxypeptidase inhibitor, and cross‐reaction with anti‐human CPM antiserum. This antiserum immunoprecipitated an average of 85% of the activity in human and baboon brain and ∼66% in dog brain. CPM copurified with myelin extracted from the brain. Consistent with results obtained in placenta and cultured kidney cells, CPM in the brain appears to be membrane‐bound via a phosphatidylinositol glycan anchor. In the peripheral nerves, the specific activity in dog sciatic nerve and in vagus was high (98 and 149 nmol/h/mg of protein, respectively). In immunohistochemical studies, glia in the brain, which appear to be oligodendrocytes or astrocytes, and the outer aspects of myelin sheaths and Schwann cells in sciatic and vagus nerves were stained. We conclude that in some areas of the CNS and the PNS, CPM is closely associated with myelin and myelin‐forming cells. Northern blot analysis revealed the presence of mRNA coding for CPM in the brain, showing that the enzyme is indeed synthesized there.