PREFERENTIAL HEME TRANSPORT THROUGH ENDOPLASMIC-RETICULUM ASSOCIATED WITH MITOCHONDRIA IN RAT-LIVER
PREFERENTIAL HEME TRANSPORT THROUGH ENDOPLASMIC-RETICULUM ASSOCIATED WITH MITOCHONDRIA IN RAT-LIVER
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DOI：
10.1016/0005-2736(94)90171-6
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发表时间：
1994-08-03
影响因子：
3.4
通讯作者：
TAKESHIGE, K
中科院分区：
文献类型：
--
作者：
ASAGAMI, H;HINO, Y;TAKESHIGE, K
通过向苯巴比妥处理的大鼠注射氨基[C-14]乙酰丙酸(ALA)，研究了从头合成的原血红素在线粒体和内质网中的转运，以评价MAER在线粒体和内质网之间的转运中的作用。在线粒体中，注射C-14-ALA后4min，标记的亚铁血红素的比放射性达到最大值。胞浆中的比放射性比微粒体中的低约2倍，这表明血红素从线粒体到内质网的胞质转运途径不占优势，因为如果血红素主要通过胞浆运输，胞浆中的比放射性应该高于微粒体中的比放射性。在4min内，MAER的比放射性高于常规微粒组分，此后，MAER的比放射性与常规微粒体组分基本相同。用破坏细胞色素P-450但不破坏细胞色素b(5)的烯丙基异丙基乙酰胺处理，细胞色素P-450的降低幅度与微粒体中的放射性程度基本相同，这表明微体中的大部分放射性标记的血红素被结合到细胞色素P-450中。这些结果表明，MAER是原血红素从线粒体向内质网运输的有利位置。
The transport of de novo synthesized protoheme into the conventional microsomal fraction and endoplasmic reticulum associated with mitochondria (MAER) was studied by injecting amino[C-14]levulinic acid (ALA) into phenobarbital-treated rats to evaluate the role of MAER in the trafficking of heme between mitochondria and endoplasmic reticulum. In mitochondria, the specific radioactivity of the radiolabeled heme reached a maximum level at 4 min after the injection of C-14-ALA. The specific radioactivity in cytosol was about 2-fold lower than that in microsomes, suggesting that the cytosolic pathway of the heme transport from mitochondria to endoplasmic reticulum is not predominant, because the specific radioactivity of heme in cytosol should be higher than that in microsomes if heme is transported mainly through cytosol. MAER showed higher specific radioactivity than the conventional microsomal fraction up to 4 min and thereafter the specific radioactivities in MAER and the conventional microsomal fraction became nearly the same. The extents of decrease in cytochrome P-450 and the radioactivity in microsomes by the treatment with allylisopropylacetamide which destroyed cytochrome P-450 but not cytochrome b(5), were essentially the same, suggesting that most of the radiolabeled heme in microsomes was incorporated into cytochrome P-450. These results suggest that MAER is a preferential site for the protoheme transport from mitochondria to endoplasmic reticulum.