Danilevich V N, Luk'ianov S A, Grishin E V
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.
Bioorg Khim. 1999 Jul;25(7):537-47.
The primary structure of the crusta gene encoding alpha-latrocrustoxin (alpha-LCT), a high molecular mass neurotoxin specific to crustaceans, was determined in the black widow spider Latrodectus mactans tredicimguttatus genome. The total length of the sequenced DNA was 4693 bp. The structural part of the black widow spider chromosome gene encoding alpha-LCT does not contain introns. The sequenced DNA contains a single extended open reading frame (4185 bp) and encodes a protein precursor of alpha-LCT, comprising 1395 aa. We assume the Met residue at position -10 relative to the N-terminal residue of Glu1 of the mature toxin to be the first one in the protein precursor. The calculated molecular mass of the precursor (156147 Da) exceeds that of the mature toxin by approximately 30 kDa. These data are in agreement with the notion that over the course of maturation the protein precursor undergoes double processing--cleavage of a decapeptide from the N-terminal part and of a approximately 200-aa fragment from the C-terminal part. alpha-LCT displayed a number of imperfect ankyrin-like repeats and areas of structural homology with earlier studied latrotoxins; the highest homology degree (62%) was revealed with alpha-latroinsectotoxin (alpha-LIT).
在红斑寇蛛（Latrodectus mactans tredicimguttatus）基因组中确定了编码α-蛛毒（α-LCT）的crusta基因的一级结构，α-蛛毒是一种对甲壳类动物具有特异性的高分子量神经毒素。测序DNA的总长度为4693 bp。红斑寇蛛染色体基因中编码α-LCT的结构部分不含内含子。测序的DNA包含一个单一的延伸开放阅读框（4185 bp），并编码α-LCT的蛋白质前体，该前体由1395个氨基酸组成。我们假定相对于成熟毒素Glu1的N端残基，位于-10位的Met残基是蛋白质前体中的第一个残基。前体的计算分子量（156147 Da）比成熟毒素的分子量大约大30 kDa。这些数据与以下观点一致，即在成熟过程中蛋白质前体经历双重加工——从N端部分切割掉一个十肽，从C端部分切割掉一个约200个氨基酸的片段。α-LCT显示出许多不完美的锚蛋白样重复序列以及与早期研究的蛛毒素的结构同源区域；与α-昆虫毒素（α-LIT）的同源性最高（62%）。
