INTEGRAL MEMBRANE POLYPEPTIDES OF RAT-LIVER PEROXISOMES - TOPOLOGY AND RESPONSE TO DIFFERENT METABOLIC STATES
INTEGRAL MEMBRANE POLYPEPTIDES OF RAT-LIVER PEROXISOMES - TOPOLOGY AND RESPONSE TO DIFFERENT METABOLIC STATES
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DOI：
10.1016/0003-9861(87)90300-6
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发表时间：
1987-05-15
影响因子：
3.9
通讯作者：
JUST, WW
中科院分区：
文献类型：
--
作者：
HARTL, FU;JUST, WW
用降血脂药氯贝特和甲状腺素对大鼠进行治疗。已知这两种药物引起过氧化物酶体增殖，并伴随过氧化物酶体脂肪酸β-肝脏中的氧化活性增加了一种主要的整体过氧化物酶体膜多肽（PMPs），其表观分子量分别为69 kDa、6倍和2倍。另一方面，甲状腺功能减退引起过氧化物酶体脂肪酸β-氧化活性，并大大降低了PMP 69在过氧化物酶体膜中的浓度。另外两个表观分子量为36和22 kDa的PMP没有受到这些治疗的影响。具有42，28和26 kDa的表观分子量的PMP被证明是来自69 kDa的多肽的活性，但尚未表征的内源性蛋白酶在分离过氧化物酶体。使用蛋白酶K和枯草杆菌蛋白酶对完整的过氧化物酶体进行有限的蛋白水解，进一步证实了69 kDa多肽的某些部分延伸到细胞质中。36-和22-kDa的多肽蛋白水解攻击的程度要低得多，因此，应该是相当深的嵌入过氧化物酶体膜内。它表明，过氧化物酶体酰基辅酶A合成酶，一个完整的PMP延伸部分进入细胞质，和PMP 69是不相同的多肽。过氧化物酶体膜与线粒体和微粒体膜的比较揭示了69-和22-kDa多肽以及过氧化物酶体脂肪酸β-过氧化物酶体的双功能蛋白质。氧化途径仅特异性地位于过氧化物酶体中。在线粒体中发现了相当数量的与抗36-kDa多肽的抗血清交叉反应的多肽。
Rats were treated with clofibrate, a hypolipidemic drug, and with thyroxine. Both drugs which are known to cause peroxisome proliferation, and a concomitant increase in peroxisomal fatty acid .beta.-oxidation activity in liver increased one of the major integral peroxisomal membrane polypeptides (PMPs), with apparent molecular mass of 69 kDa, six- and twofold, respectively. On the other hand hypothyroidism caused a decrease in peroxisomal fatty acid .beta.-oxidation activity and considerably lowered the concentration of PMP 69 in the peroxisomal membrane. Two other PMPs with apparent molecular masses of 36 and 22 kDa were not influenced by these treatments. The PMPs with apparent molecular masses of 42, 28, and 26 kDa were shown to be derived from the 69-kDa polypeptide by the activity of a yet uncharacterized endogenous protease during isolation of peroxisomes. Limited proteolysis of intact peroxisomes using proteinase K and subtilisin further substantiated that some portion of the 69-kDa polypeptide extends into the cytoplasm. The 36- and the 22-kDa polypeptides were accessible to proteolytic attack to a much lower extent and, therefore, are supposed to be rather deeply embedded within the peroxisomal membrane. It is demonstrated that peroxisomal acyl-CoA synthetase, an integral PMP extending partially into the cytoplasm, and PMP 69 are not identical polypeptides. Comparison of the peroxisomal membrane with that of mitochondria and microsomes revealed that the 69- and 22-kDa polypeptides as well as the bifunctional protein of the peroxisomal fatty acid .beta.-oxidation pathway were specifically located only in peroxisomes. Considerable amounts of a polypeptide cross-reacting with the antiserum against the 36-kDa polypeptide were found in mitochondria.