VITAMIN-K DEPENDENT CARBOXYLASE - SUBCELLULAR LOCATION OF THE CARBOXYLASE AND ENZYMES INVOLVED IN VITAMIN-K METABOLISM IN RAT-LIVER
VITAMIN-K DEPENDENT CARBOXYLASE - SUBCELLULAR LOCATION OF THE CARBOXYLASE AND ENZYMES INVOLVED IN VITAMIN-K METABOLISM IN RAT-LIVER
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DOI：
10.1021/bi00547a019
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发表时间：
1980-01-01
期刊：
影响因子：
2.9
通讯作者：
SUTTIE, JW
中科院分区：
文献类型：
--
作者：
CARLISLE, TL;SUTTIE, JW
维生素K依赖性羧化的外源性肽底物和内源性蛋白质底物，维生素K的环氧化和还原的维生素K环氧化物测定从大鼠肝脏的亚细胞组分。粗糙微粒体组分高度富集所有4种活性;在光滑微粒体中发现较低水平。线粒体、细胞核和胞质溶胶的活性可以忽略不计。线粒体、细胞核和胞质溶胶的活性可忽略不计。向完整微粒体中添加0.2% Triton X-100会对肽底物的羧化产生10至20倍的刺激。这种明显的潜伏期表明，羧化酶的活性位点可能只能从微粒体膜的内腔进入。的羧化酶的内腔面向的方向也支持其不可及的胰蛋白酶在完整的微粒体与显着抑制胰蛋白酶在洗涤剂渗透微粒体。维生素K环氧酶和环氧化物还原酶的活性也受到抑制胰蛋白酶更有效地透化比在完整的微粒体，虽然在胞质表面也表明一定程度的曝光。羧化显然是凝血酶原合成的早期事件，主要发生在粗面内质网膜的管腔侧。维生素K环氧化还原循环酶的位置与其在羧化反应中可能的作用一致。
Vitamin K dependent carboxylation of an exogenous peptide substrate and endogenous protein substrates, vitamin K epoxidation and reduction of vitamin K epoxide were measured in subcellular fractions from rat liver. The rough microsomal fraction was highly enriched in all 4 activities; lower levels were found in smooth microsomes. Mitochondria, nuclei, and cytosol had negligible activities. Mitochondria, nuclei and cytosol had negligible activities. Addition of 0.2% Triton X-100 to intact microsomes resulted in a 10 to 20-fold stimulation in carboxylation of a peptide substrate. This marked latency suggests that the active site of the carboxylase may be accessible only from the lumen of the microsomal membrane. A lumen-facing orientation of the carboxylase was also supported by its inaccessibility to trypsin in intact microsomes contrasted with marked inhibition by trypsin in detergent-permeabilized microsomes. Vitamin K epoxidase and epoxide reductase activities were also inhibited by trypsin much more effectively in permeabilized than in intact microsomes, although some degree of exposure at the cytosolic surface was also indicated. Carboxylation is apparently an early event in prothrombin synthesis occurring primarily on the lumen side of the rough endoplasmic reticulum membrane. The location of the vitamin K epoxidation-reduction cycle enzymes is consistent with their possible role in the carboxylation reaction.