Targeting of the hepatitis B virus precore protein to the endoplasmic reticulum membrane: after signal peptide cleavage translocation can be aborted and the product released into the cytoplasm.
Targeting of the hepatitis B virus precore protein to the endoplasmic reticulum membrane: after signal peptide cleavage translocation can be aborted and the product released into the cytoplasm.
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DOI：
10.1083/jcb.106.4.1093
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发表时间：
1988-04
期刊：
影响因子：
--
通讯作者：
Walter P
中科院分区：
文献类型：
--
作者：
Garcia PD;Ou JH;Rutter WJ;Walter P
乙型肝炎病毒（HBV）主要核心蛋白是一种参与核酸结合的病毒结构蛋白。其编码序列在蛋白质的氨基端包含29个密码子的延伸（“前孔”区），这些密码子存在于病毒转录本的一小部分中。该区域在哺乳动物和禽类乙肝病毒中是进化保守的，这表明它具有重要的功能，尽管至少在鸭乙肝病毒中，它已被证明对感染性病毒粒子的复制不是必需的。通过对蛋白质跨内质网膜易位的体外分析，我们发现HBV基因组的前孔区编码一个信号序列。该信号序列被信号识别粒子识别，其将新生的前体细胞蛋白靶向到内质网膜上，其效率与其他哺乳动物分泌蛋白相当。一个19个氨基酸的信号肽被微体膜管腔侧的信号肽酶去除，生成一个类似于HBV主要核心蛋白的蛋白质，但在其氨基端含有10个来自前孔区的额外氨基酸。令人惊讶的是，我们发现70- 80%的信号肽酶裂解产物定位于微粒体囊泡的细胞质一侧，而与膜无关。我们的结论是，易位被一个未知的机制终止，然后蛋白质脱离易位机制并被释放回细胞质中。因此，一个细胞质处理的蛋白质被创造，其氨基端是由信号肽酶切割产生的。剩余的20-30%似乎完全转移到微粒体的腔内。缺失突变体缺乏前体细胞蛋白的羧基末端核酸结合域，类似地在微粒体的管腔和细胞质室之间分裂，表明这个高电荷域不是导致易位失败的原因。我们讨论了我们的发现对蛋白质易位过程的影响，并提出了在病毒生命周期中的可能作用。
The major hepatitis B virus (HBV) core protein is a viral structural protein involved in nucleic acid binding. Its coding sequence contains an extension of 29 codons (the "precore" region) at the amino terminus of the protein which is present in a fraction of the viral transcripts. This region is evolutionarily conserved among mammalian and avian HBVs, suggesting it has functional importance, although at least for duck HBV it has been shown to be nonessential for replication of infectious virions. Using in vitro assays for protein translocation across the endoplasmic reticulum membrane, we found that the precore region of the HBV genome encodes a signal sequence. This signal sequence was recognized by signal recognition particle, which targeted the nascent precore protein to the endoplasmic reticulum membrane with efficiencies comparable to those of other mammalian secretory proteins. A 19-amino acid signal peptide was removed by signal peptidase on the lumenal side of the microsomal membrane, generating a protein similar to the HBV major core protein, but containing 10 additional amino acids from the precore region at its amino terminus. Surprisingly, we found that 70- 80% of this signal peptidase-cleaved product was localized on the cytoplasmic side of the microsomal vesicles and was not associated with the membranes. We conclude that translocation was aborted by an unknown mechanism, then the protein disengaged from the translocation machinery and was released back into the cytoplasm. Thus, a cytoplasmically disposed protein was created whose amino terminus resulted from signal peptidase cleavage. The remaining 20-30% appeared to be completely translocated into the lumen of the microsomes. A deletion mutant lacking the carboxy-terminal nucleic acid binding domain of the precore protein was similarly partitioned between the lumen of the microsomes and the cytoplasmic compartment, indicating that this highly charged domain is not responsible for the aborted translocation. We discuss the implications of our findings for the protein translocation process and suggest a possible role in the virus life cycle.
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影响因子：
7.8
作者：
Walter, P;Blobel, G
通讯作者：
Blobel, G
影响因子：
5.4
作者：
ROOSSINCK, MJ;SIDDIQUI, A
通讯作者：
SIDDIQUI, A
DOI：
10.1089/dna.1.1984.3.479
发表时间：
1984-01-01
期刊：
DNA-A JOURNAL OF MOLECULAR & CELLULAR BIOLOGY
影响因子：
--
作者：
ZOLLER, MJ;SMITH, M
通讯作者：
SMITH, M
DOI：
10.1083/jcb.91.2.545
发表时间：
1981-11
期刊：
The Journal of cell biology
影响因子：
--
作者：
Walter P;Ibrahimi I;Blobel G
通讯作者：
Blobel G
DOI：
10.1073/pnas.83.6.1578
发表时间：
1986-03-01
影响因子：
11.1
作者：
OU, JH;LAUB, O;RUTTER, WJ
通讯作者：
RUTTER, WJ