关键词: 家蚕, 精氨酸激酶, 基因结构, 表达, 转录因子

Abstract: Arginine kinase is the major guanidino kinase found in invertebrates and plays a key role in the energy-releasing mechanism. According to the sequence of silkworm EST generated by the large-scale cDNA sequencing, the full-length cDNA of arginine kinase was isolated from the silkworm by 5′RACE ,named as BmAK (GeneBank accession number: DQ272299). BmAK cDNA has 1268 bp and contains an open reading frame encoding a 355 amino acid protein. The profile analysis using Prosite suggests that the active sequence is lies in between 270 to 276: CPTNLGT and the active site is Cys270. BmAK contains a pair of highly conserved amino acids (D61 and R192) that form an ion pair which is essential for the expression of synergism in substrate binding by AKs. The BmAK gene and its 5′-upstream sequence were cloned and sequenced. The BmAK gene contains only 2 exons and 1 intron. The BmAK promoter contains no TATA box, but potential binding sites for the transcription factors were detected in both forward and reverse orientation : HSF、BRCZ、E74A、HB、FTZ、DFD、ZESTE、DL、STAT、PRD-HD. The expression pattern of BmAK in silkworm tissues was analyzed by Northern blotting, the transcript was detected in all tissues examined including midgut, fat body, skin, silkgland and abdominal legs .It appeared that the expression of the transcript was the highest in abdominal legs and was relatively lower in midgut, skin and silkgland . The expression amount of BmAK in different stages was different and the analysis on the transcription factor binding sites in the BmAK 5′flanking region and the expression pattern of BmAK shows that the developmental expression of BmAK gene is possible under the influence of ecdysone.

Key words: Bombyx mori, Arginine kinase, Gene structure, Expression, Transcription element