| Sodium/iodide symporter (NIS) is a kind of glucoprotein located in the basolateral membrane of thyroid gland follicular cells, catalyzing active I" transport into thyroid cells, the first step in thyroid hormone biogenesis. NIS plays a critical role in thyroid pathophysiology and recently it has become a focus in the field about prevention and cure of iodine-deficiency disease and other thyroid diseases.Firstly, full-length sequence encoding rat NIS gene was obtained by DNA amplification using cDNA library derived from rat thyroid tissues as template, and then it was cloned into pGEM-T Easy vector. Secondly, the target sequence was inserted respectively into prokaryotic non-fusion expression vector pBV220 and prokaryotic fusion expression vector pGEX-3X. Thirdly, recombinant plasmid pBV220/NIS and pGEX-3X/NIS were transformed into corresponding competent E.coli cells DH5a and BL21 (DE3). It was found that prospective protein was generated apparently in BL21 cell while vacant in DH5a cell according to SDS-PAGE analysis. Western blotting with anti-GST antibody tested and revealed that the 93-KD fusion protein was GST-NIS. In the end, after optimization of expressing conditions as well as segregation ?denaturation and renaturation of inclusion body, the yield of solvable fusion protein referred above reached about 1.02 g/L medium.In the present work, rat NIS gene was expressed in E.coli successfully, which lay a foundation for producing rNIS protein by genetic engineering.
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