In this study,to clarify the bioactive polypeptides included in the skins and secretions of Bufo,we screened the Japanese toad(Bufo japonicus formosus) skin cDNA library by colony polymerase chain reaction(PCR),and obtained a transcript of 1 075 bp consisting of 1 37 bp 5′ untranslated region(UTR),515 bp 3′ UTR and a 423 bp open reading frame(ORF) encoding a polypeptide of 140 amino acid residues(GenBank accession number: KF359945).Homolog analysis showed a 70%–96% homology with sterol carrier protein-2(SCP-2) present in other animals,which is implicated in lipid metabolism of other organisms.The gene SCP-2 of Chinese toad(B.gargarizans) was cloned from a first strand cDNA of Bufo skin(GenBank accession number: KF381341) via PCR,whose encoding polypeptide has only one amino acid difference from that of Japanese toad.Tissue distribution analysis showed that SCP-2 expressed in all organs tested,though in the liver and spleen it manifested lower expression than in other organs.These findings might indicate SCP-2 being one of the active ingredients in toad skin.These findings may in turn have implications for further drug development from traditional Chinese medicine sources.
Yu-Cheng JIHui ZHUGEShan-Shan ZHANGShu-Fang ZHANGXian-Yu Yang
半乳糖凝聚素-3(Galectin-3,Gal-3)是一种多功能蛋白,参与机体内的多种生命活动过程。为分析大鼠Rattus norvegicus gal-3 c DNA分子多样性,在分析Gen Bank注册的大鼠gal-3 c DNA序列的同时,从三只不同大鼠个体的肝脏第一链c DNA,共计9个独立实验中克隆gal-3开放阅读框OFR(Open reading frame)。分析结果表明,在已注册的序列中存在1个单核苷酸多态性(Single nucleotide polymorphism,SNP)。本实验从1-3号大鼠肝脏分别获得118、95和120个克隆,新发现1处缺失和5处SNP,共克隆17个不同的gal-3 ORF,其中仅1个克隆与已报告大鼠gal-3 c DNA的ORF完全相同。从1号和3号个体肝脏中分别克隆11和14个不同的gal-3 ORF,揭示大鼠gal-3 c DNA存在个体水平的分子多样性。
