Morita Yuka, Hiramatsu Naoshi, Fujita Toshiaki, Amano Haruna, Todo Takashi, Hara Akihiko
Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan.
Zoolog Sci. 2011 Mar;28(3):215-24. doi: 10.2108/zsj.28.215.
Alpha-fetoprotein (AFP) is a fetal glycoprotein that is known as a biomarker for monitoring pregnancy in many mammalian species. However, characterization of AFP has not yet been undertaken in any cetacean species. Here, we purified AFP from the serum of fetal striped dolphin by chemical precipitation followed by a combination of immunoadsorbent column chromatography and gel filtration. The molecular masses of native and denatured dolphin AFP were estimated to be ∼78,000 Da by gel filtration and ∼68,000 Da by SDS-PAGE, respectively, representing typical masses reported for mammalian AFPs. In fetal serum, only the AFP band (∼68,000 Da) appeared to be immunoreactive to an antiserum against purified dolphin AFP, indicating sufficient specificity for the development of an AFP immunoassay. Full-length cDNA encoding for the dolphin AFP was cloned from fetal liver and revealed an open reading frame comprising 610 amino acid residues, which included a putative signal peptide of 18 amino acid residues. This was followed by a sequence identical to the N-terminus of purified AFP. The deduced amino acid sequence of dolphin AFP showed more than 80% identity to those of other mammalian AFPs. To our knowledge, the present report represents the first identification and characterization of AFP from any cetacean species.
甲胎蛋白（AFP）是一种胎儿糖蛋白，在许多哺乳动物物种中作为监测妊娠的生物标志物为人所知。然而，尚未对任何鲸类物种的AFP进行表征。在此，我们通过化学沉淀，随后结合免疫吸附柱色谱和凝胶过滤，从胎儿条纹海豚的血清中纯化了AFP。通过凝胶过滤估计天然和变性海豚AFP的分子量分别约为78,000 Da，通过SDS-PAGE估计约为68,000 Da，这代表了哺乳动物AFP报道的典型分子量。在胎儿血清中，只有AFP条带（约68,000 Da）似乎对针对纯化海豚AFP的抗血清具有免疫反应性，这表明对开发AFP免疫测定具有足够的特异性。从胎儿肝脏中克隆了编码海豚AFP的全长cDNA，其显示出一个包含610个氨基酸残基的开放阅读框，其中包括一个18个氨基酸残基的推定信号肽。随后是与纯化AFP的N端相同的序列。海豚AFP推导的氨基酸序列与其他哺乳动物AFP的氨基酸序列显示出超过80%的同一性。据我们所知，本报告代表了首次从任何鲸类物种中鉴定和表征AFP。
