摘要
金属硫蛋白是一种普遍存在于生物体内的低分子量、半胱氨酸含量丰富、易于被外界刺激诱导的金属结合蛋白。采用表达序列标签法,结合cDNA末端快速扩增技术,首次获得了海湾扇贝金属硫蛋白(AiMT)的全长cDNA序列。该序列全长787bp,5′UTR(UntranslatedRegion)为79bp,3′UTR为270bp,开放阅读框(OpenReadingFrame,ORF)长度为438bp,可编码145个氨基酸。在其编码的氨基酸序列中半胱氨酸含量丰富,甘氨酸含量也较高,芳香族氨基酸含量低,不含组氨酸,存在有无脊椎动物和软体动物金属硫蛋白的特征序列CKCXXX-CXCX,C-末端的氨基酸序列也符合软体动物金属硫蛋白标签序列C-x-C-x(3)-C-T-G-x(3)-C-x-C-x(3)-C-x-C-K。序列特征分析表明,该序列具备金属硫蛋白的典型特征,是金属硫蛋白家族的成员。
Metallothioneins （MTs）are low molecular weight, cysteine-rich, inducible metal-binding proteins found in a variety of organisms. MTs have many important biological functions acted as a protective role against excess reactive heavy metal ions, free radical scavengers and reservoir of essential metals that can be donated to other metalloproteins. A partial sequence of the bay scallop Argopecten irradians metallothionein （named as AiMT）gene was identified from A. irradians cDNA library using expressed sequence tag method. A pair of gene-specific primers was designed according to this sequence and the full-length of AiMT cDNA was obtained using rapid amplification of cDNA end technique. The full-length cDNA of AiMT was of787bp including a 5＇untranslated region（UTR） of 79bp, a 3＇UTR of 270 bp and an open reading frame（ORF） of 438bp encoding a polypeptide of 145 amino acids. The predicted amino acid sequence of AiMT contained 40 cysteine residues organized in Cys - X（n）-Cys（ n = 1-3 ） motif as classically described for MTs. The contents of cysteine, glycine and phenylalanine in the AiMT amino acids sequence were 27.6% , 13.1% and 2.1% respectively while no histidine residue was found. The CKCXXXCXCX motif, a conserved feature for invertebrate and molluscan MT, was found in two regions of the AiMT. A specific pattern of mollusca MT C-x-C-x（3）-C- T-G-x（3）-C-x-C-x（3）-C-x-C-K located at the C-terminal. The result of sequence analysis indicated that AiMT was the member of metallothionein family.
出处
《海洋与湖沼》
CAS
CSCD
北大核心
2006年第5期444-449,共6页
Oceanologia Et Limnologia Sinica
基金
863国家高技术研究发展计划资助项目
2002AA626020号
国家自然科学基金资助项目
40276045号
