Faure G, Choumet V, Bouchier C, Camoin L, Guillaume J L, Monegier B, Vuilhorgne M, Bon C
Unité des Venins, Institut Pasteur, Paris, France.
Eur J Biochem. 1994 Jul 1;223(1):161-4. doi: 10.1111/j.1432-1033.1994.tb18978.x.
Crotoxin, the main toxin from the venom of the South American rattlesnake Crotalus durissus terrificus, is a beta-neurotoxin which consists of the non-covalent association of two subunits: a phospholipase A2 subunit B (CB), and a non-enzymic subunit A (CA). We have previously purified and characterized several isoforms of each subunit of crotoxin in the venom collected from numerous snakes. Furthermore, three cDNAs encoding two CB isoforms and the precursor, pro-CA, of subunit A have been isolated from a cDNA library prepared from a single venom gland of Crotalus durissus terrificus. The aim of this study is to analyse an individual snake venom from an animal that has been used to construct a cDNA library. Several isoforms of subunit A and two isoforms of subunit B were isolated and compared to purified and characterized subunit isoforms from pooled venom. The result of this study showed that the multiplicity and the diversity of crotoxin isoforms result from post-translational modifications occurring on a precursor and from the expression of different messenger RNAs present in an individual snake. It allowed for the identification of the two CB isoforms encoding cDNAs expressed in the individual venom with two isoforms from pooled venom, CBc and probably CBa2, that belong to two classes of crotoxin complexes which can be distinguished biochemically and pharmacologically.
响尾蛇毒素是南美响尾蛇（Crotalus durissus terrificus）毒液中的主要毒素，是一种β-神经毒素，由两个亚基非共价结合而成：一个磷脂酶A2亚基B（CB）和一个非酶亚基A（CA）。我们之前已经从大量蛇类的毒液中纯化并鉴定了响尾蛇毒素各亚基的几种同工型。此外，从南美响尾蛇单个毒腺制备的cDNA文库中分离出了三个编码两个CB同工型以及亚基A的前体蛋白原CA的cDNA。本研究的目的是分析来自用于构建cDNA文库的动物的单个蛇毒。分离出了亚基A的几种同工型和亚基B的两种同工型，并与从混合毒液中纯化和鉴定的亚基同工型进行了比较。本研究结果表明，响尾蛇毒素同工型的多样性和差异性源于前体蛋白的翻译后修饰以及单个蛇体内存在的不同信使RNA的表达。这使得能够将在单个毒液中表达的两个CB同工型编码cDNA与来自混合毒液的两种同工型CBc和可能的CBa2进行鉴定，这两种同工型属于两类可通过生化和药理学方法区分的响尾蛇毒素复合物。
