Molecular cloning and characterization of Bombyx mori sterol carrier protein x/sterol carrier protein 2 (SCPx/SCP2) gene
Molecular cloning and characterization of Bombyx mori sterol carrier protein x/sterol carrier protein 2 (SCPx/SCP2) gene
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DOI：
10.1080/10425170600886706
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发表时间：
2006-10-01
期刊：
影响因子：
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通讯作者：
Xia, Qing-You
中科院分区：
文献类型：
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作者：
Gong, Jing;Hou, Yong;Xia, Qing-You
胆固醇运输是昆虫中一个非常重要的过程。我们分离了家蚕甾醇载体蛋白 x (BmSCPx) cDNA 和甾醇载体蛋白 2 (BmSCP2) cDNA：编码 SCPx（一种 3-酮酰辅酶 A 硫解酶）的 1.7 kb 克隆，以及可能编码 SCP2（被认为是细胞内脂质转移蛋白）的 0.6 kb 克隆。有趣的是，相同的基因 SCPx/SCP2 在家蚕中通过选择性剪接机制编码两种类型的转录本。 SCPx mRNA跨越基因组中的两个外显子，SCPx cDNA的概念翻译编码536个氨基酸的蛋白质，其中包含硫解酶结构域和SCP2结构域。而 SCP2 mRNA 部分包含第一个外显子，并且 SCP2 是仅包含 SCP2 结构域的 146 个氨基酸。 BmSCPx 和 BmSCP2 在 C 端区域都有假定的过氧化物酶体靶向信号。 BmSCPx 与斜纹夜蛾 SCPx 和人类 SCPx 分别具有 94% 和 72% 的相似性。 RTPCR 分析表明，在所有分析的组织中均检测到了 BmSCP2 的转录本。 BmSCPx 转录仅在中肠和马氏小管中表达。然而，BmSCPx 和 BmSCP2 在最后龄幼虫的中肠中表达强烈。 BmSCPx 和 BmSCP2 的组织特异性表达模式与这些蛋白质在胆固醇代谢中的作用一致。结果表明，SCPx/SCP2可能在家蚕甾醇吸收和细胞内载体中发挥关键作用。
Cholesterol transport is a very important process in insect. We have isolated the Bombyx mori sterol carrier protein x (BmSCPx) cDNA and sterol carrier protein 2 (BmSCP2) cDNA: a 1.7 kb clone encoding SCPx, a 3-ketoacyl CoA thiolase, and 0.6 kb clone presumably encoding SCP2, which is thought to be an intracellular lipid transfer protein. Interestingly, the identical gene SCPx/SCP2 encodes the two types of transcripts by alternative splicing mechanism in Bombyx mori. The SCPx mRNA spans two exons in genome, and conceptual translation of the SCPx cDNA encodes a protein of 536 amino acids, which contains a thiolase domain and a SCP2 domain. Whereas the SCP2 mRNA partly lakes the first exon, and the SCP2 is a 146 amino acids containing a SCP2 domain only. Both BmSCPx and BmSCP2 have a putative peroxisomal targeting signal in the C-terminal region. BmSCPx shares 94 and 72% similarity to Spodoptera littoralis SCPx and human SCPx, respectively. RTPCR analysis reveals that transcripts of BmSCP2 were detected in all tissues analyzed. BmSCPx transcription expressed only in midgut and malpighian tubules. However, the BmSCPx and BmSCP2 express strong in midgut during the last instar larvae. The tissue-specific expression pattern of BmSCPx and BmSCP2 is consistent with a role for these proteins in cholesterol metabolism. The results suggest that SCPx/SCP2 may play a key role in sterol absorption and intracellular carrier in silkworm.