The primary structure and carbohydrate specificity of a beta-galactosyl-binding lectin from toad (Bufo arenarum Hensel) ovary reveal closer similarities to the mammalian galectin-1 than to the galectin from the clawed frog Xenopus laevis
The primary structure and carbohydrate specificity of a beta-galactosyl-binding lectin from toad (Bufo arenarum Hensel) ovary reveal closer similarities to the mammalian galectin-1 than to the galectin from the clawed frog Xenopus laevis
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DOI：
10.1074/jbc.271.51.33083
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发表时间：
1996-12-20
影响因子：
4.8
通讯作者：
Vasta, GR
中科院分区：
文献类型：
--
作者：
Ahmed, H;Pohl, J;Vasta, GR
从蟾蜍（Bufo arenarum Hensel）卵巢中提取的一种凝集素的主要结构、碳水化合物特异性和总体生化特性的详细表征，为凝集素家族的结构和进化方面提供了新的信息。该凝集素由134个氨基酸（计算质量为14,797道尔顿）组成的相同单链多肽亚基组成，其n端残基丙氨酸被n -乙酰化。与已知的凝集素序列相比，沙草凝集素与牛脾脏凝集素-1的一致性最高（整个分子为48%，碳水化合物识别结构域（CRD）为77%），但令人惊讶的是，与非洲爪蟾皮肤的凝集素的一致性较低（整个分子为38%，CRD为47%）（Marschal， P., Herrmann， J., Leffler， H., Barondes， S. H., and Cooper， D. N. W. (1992) J. Biol.）。化学，267,12942-12949)。与X. laevis凝集素不同，B. arenum凝集素对n-乙酰乳胺、人血A型四糖和相对于乳糖的Gal - 1,3 galnac的结合活性，与观察到的凝集素-1亚组和那些具有“保守”（I型）CRDs的凝集素的结合活性一致（Ahmed， H., and Vasta， G. R.（1994）糖生物学4,545 -549）。此外，蟾蜍的凝集素有6个半胱氨酸残基中的3个，这些残基在所有哺乳动物的凝集素-1中都是保守的，但在X. laevis、鱼类和无脊椎动物的凝集素中却没有。基于沙arenum凝集素与牛脾脏凝集素-1和X. laevis皮肤凝集素的同源性，应该得出结论，在凝集素家族中，原始结构的保存与源物种之间的系统发育距离之间的关系可能不像其他地方提出的那样直接相关（Hirabayashi， J., and Kasai， K. (1993) Glycobiology 3,297 -304）。此外，以arenarum B.卵巢凝集素为代表的保守型（I型）凝集素和以X. laevis 16-kDa凝集素为代表的“可变型”（II型）凝集素，在现存两栖动物类群中明显构成了不同的亚群，并可能在弦动物谱系进化的早期就出现了分化。
The detailed characterization of a galectin from the toad (Bufo arenarum Hensel) ovary in its primary structure, carbohydrate specificity, and overall biochemical properties has provided novel information pertaining to structural and evolutionary aspects of the galectin family. The lectin consists of identical single-chain polypeptide subunits composed of 134 amino acids (calculated mass, 14,797 daltons), and its N-terminal residue, alanine, is N-acetylated. When compared to the sequences of known galectins, the B. arenarum galectin exhibited the highest identity (48% for the whole molecule and 77% for the carbohydrate recognition domain (CRD)) with the bovine spleen galectin-1, but surprisingly less identity (38% for the whole molecule and 47% for the CRD) with a galectin from Xenopus laevis skin (Marschal, P., Herrmann, J., Leffler, H., Barondes, S. H., and Cooper, D. N. W. (1992) J. Biol. Chem. 267, 12942-12949). Unlike the X. laevis galectin, the binding activity of the B. arenarum galectin for N-acetyllactosamine, the human blood group A tetrasaccharide and Gal beta 1,3GalNAc relative to lactose, was in agreement with that observed for the galectin-1 subgroup and those galectins having ''conserved'' (type I) CRDs (Ahmed, H., and Vasta, G. R. (1994) Glycobiology 4, 545-549). Moreover, the toad galectin shares three of the six cysteine residues that are conserved in all mammalian galectins-1, but not in the galectins from X. laevis, fish, and invertebrates described so far. Based on the homologies of the B. arenarum galectin with the bovine spleen galectin-1 and X. laevis skin galectin, it should be concluded that within the galectin family the correlation between conservation of primary structure and phylogenetic distances among the source species may not be a direct one as proposed elsewhere (Hirabayashi, J., and Kasai, K. (1993) Glycobiology 3, 297-304). Furthermore, galectins with conserved (type I) CRDs, represented by the B. arenarum ovary galectin, and those with ''variable'' (type II) CRDs, represented by the X. laevis 16-kDa galectin, clearly constitute distinct subgroups in the extant amphibian taxa and may have diverged early in the evolution of chordate lineages.