新丰毒蛋白——一种新的具有活性小A链的核糖体失活蛋白(英文)

Cinphorin: a Novel Type Ⅱ Ribosome-inactivating Protein With Miniature Active A-chain

辛纳毒蛋白是从香樟种子中分离的一种Ⅱ核糖体失活蛋白 .最近 ,从香樟种子中还分离到另一种微型双链核糖体失活蛋白 ,命名为新丰毒蛋白 .还原的新丰毒蛋白表现出与还原的辛纳毒蛋白同样的RNAN 糖苷酶和体外对抑制蛋白质翻译的活力 .新丰毒蛋白的B链与辛纳毒蛋白的B链具有同样的分子质量和相同的N端 10个氨基酸序列 .它的A链N端 10个氨基酸序列也与辛纳毒蛋白的A链完全一致 ,并且C端与辛纳毒蛋白的A链一样具有半胱氨酸 ,但是它的分子质量却只有辛纳毒蛋白A链的一半 .RT PCR和RNA印迹结果表明体内不存在新丰毒蛋白的mRNA .推测新丰毒蛋白是从辛纳毒蛋白通过蛋白质剪接而产生的 。

Cinnamomin is a type Ⅱ ribosome inactivating protein (RIP) isolated from the seed of camphor tree ( Cinnamomum camphora ). Recently, a small RIP named as cinphorin was isolated from the seed of camphor tree. The reduced cinphorin exhibited the RNA N glycosidase activity and inhibitory activity to protein synthesis in vitro like the reduced cinnamomin did. Cinphorin B chain exhibited the same N terminal 10 amino acid sequence and molecular mass as the B chain of cinnamomin. Its A chain exhibited the same 10 N terminal amino acid sequence and owned a C terminal cysteine residue linked to the B chain, but the molecular mass of cinphorin A chain was only half of cinnamomin A chain. RT PCR and Northern blotting revealed that there was no corresponding mRNA of cinphorin. Cinphorin is probably produced from cinnamomin by protein splicing.