Isolation and characterization of cDNAs encoding the heavy chain of human inter-alpha-trypsin inhibitor (I alpha TI): unambiguous evidence for multipolypeptide chain structure of I alpha TI.
Isolation and characterization of cDNAs encoding the heavy chain of human inter-alpha-trypsin inhibitor (I alpha TI): unambiguous evidence for multipolypeptide chain structure of I alpha TI.
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DOI：
10.1073/pnas.84.23.8272
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发表时间：
1987-12
影响因子：
11.1
通讯作者：
Jean-Philippe Salier;M. Diarra‐Mehrpour;R. Sesboüé;J. Bourguignon;R. Benarous;I. Ohkubo;Sumiko Kurachi;Kotoku Kurachi;Josiane Martin
中科院分区：
文献类型：
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作者：
Jean-Philippe Salier;M. Diarra‐Mehrpour;R. Sesboüé;J. Bourguignon;R. Benarous;I. Ohkubo;Sumiko Kurachi;Kotoku Kurachi;Josiane Martin
人间α-胰蛋白酶抑制剂（I α TI）是一种Mr为180，000的血浆糖蛋白，被描述为单链多肽。然而，最近，我们提出I α TI可能由两个单独的mRNA合成的重（H）链（Mr = 95，000）和轻（L）链（Mr = 40，000）组成。在本研究中，我们的特点是cDNA的H链的I α TI。这些cDNA共同覆盖了具有单个开放阅读框的两个序列（长度为977和1450个碱基对）。推导的氨基酸序列高度同源，并与纯化血清I α TI的部分氨基酸序列完全匹配。用H链或L链cDNA作为探针的肝RNA的RNA印迹分析清楚地鉴定了3.3和1.3内切酶的两种不同的mRNA，其分别对应于H链或L链。Poly（A）+RNA与编码Mr 90，000 - 95，000多肽链的H链cDNA杂交选择。这些结果明确地确定I α TI由多多肽组成，可能包括一条H链和两条L链。H链含有潜在的钙结合位点，也是与巯基蛋白酶抑制剂的拟议反应位点同源的区域。这些数据表明I α TI是一种复杂的多功能蛋白质。H和L链的mRNA仅在肝脏中发现。
Human inter-alpha-trypsin inhibitor (I alpha TI) is a plasma glycoprotein of Mr 180,000, which has been described as a single polypeptide chain. Recently, however, we proposed that I alpha TI might be composed of a heavy (H) chain (Mr = 95,000) and a light (L) chain (Mr = 40,000) synthesized by two separate mRNAs. In the present study we have characterized cDNAs for the H chain of I alpha TI. These cDNAs collectively covered two sequences (977 and 1450 base pairs in length) with single open reading frames. The deduced amino acid sequences were highly homologous to each other and well matched with partial amino acid sequences obtained from purified serum I alpha TI. RNA blot analyses of liver RNAs with H- or L-chain cDNAs as probes clearly identified two distinct mRNAs of 3.3 and 1.3 kilobases, which corresponded to H or L chain, respectively. Poly(A)+ RNAs hybrid-selected with H-chain cDNAs coded for polypeptide chains of Mr 90,000-95,000. These results unambiguously establish that I alpha TI is made of multipolypeptides, possibly including one H and two L chains. The H chain contains potential calcium-binding sites and also regions homologous to the proposed reactive site for thiol-proteinase inhibitors. These data indicate that I alpha TI is a complex, multifunctional protein. mRNAs for both the H and L chains were found only in liver.