Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-8572, Japan.
Professor emeritus, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
Mar Drugs. 2018 Jun 29;16(7):224. doi: 10.3390/md16070224.
Pufferfish saxitoxin and tetrodotoxin (TTX) binding protein (PSTBP) is a glycoprotein that we previously isolated from the blood plasma of the pufferfish ; this protein was also detected in seven species of the genus . We proposed that PSTBP is a carrier protein for TTX in pufferfish; however, PSTBP had not yet been found in genera other than . In this study, we investigated the presence of PSTBP-like proteins in the toxic pufferfish , , , and . On the basis of ultrafiltration experiments, TTX was found to be present and partially bound to proteins in the plasma of these pufferfish, and Western blot analyses with anti-PSTBP antibody revealed one or two bands per species. The observed decreases in molecular mass following deglycosylation with glycopeptidase F suggest that these positive proteins are glycoproteins. The molecular masses of the deglycosylated proteins detected in the three species were larger than that of PSTBP in the genus , whereas the two bands detected in had molecular masses similar to that of tributyltin-binding protein-2 (TBT-bp2). The -terminal amino acid sequences of 23⁻29 residues of these detected proteins were all homologous with those of PSTBP and TBT-bp2.
河豚鱼石房蛤毒素和河豚毒素（TTX）结合蛋白（PSTBP）是一种糖蛋白，我们之前从河豚鱼的血浆中分离出来；这种蛋白质也在 属的七种物种中被检测到。我们提出 PSTBP 是河豚鱼中 TTX 的载体蛋白；然而，除了 属之外，PSTBP 尚未在其他属中发现。在这项研究中，我们研究了有毒河豚鱼 、 、 、 中 PSTBP 样蛋白的存在。基于超滤实验，发现 TTX 存在于这些河豚鱼的血浆中，并与部分蛋白质结合，用抗 PSTBP 抗体进行的 Western blot 分析显示每个物种有一个或两个条带。用糖苷酶 F 进行糖基化处理后观察到的分子量降低表明这些阳性蛋白是糖蛋白。在三种 物种中检测到的去糖基化蛋白的分子量大于 属中的 PSTBP，而在 中检测到的两条带的分子量与三丁基锡结合蛋白-2（TBT-bp2）相似。这些检测到的蛋白质的 23-29 个残基的 -末端氨基酸序列都与 PSTBP 和 TBT-bp2 的序列同源。
