Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
Mol Biol Rep. 2012 Apr;39(4):4879-88. doi: 10.1007/s11033-011-1283-3. Epub 2011 Nov 19.
Arginine kinase (AK) is an important phosphotransferase that plays a critical role in energy metabolism in invertebrates. In this paper, the cDNA of AK (designated as PtAK) was identified from the eyestalk cDNA library of swimming crab Portunus trituberculatus. The full-length cDNA was 1,479 bp, containing an open reading frame of 1,074 bp that coded for 357 amino acids. The estimated molecular mass of mature PtAK was 40.30 kDa and theoretical isoelectric point was 6.18. Amino acid sequence alignment showed that PtAK had very high similarity with other shrimp and crab AKs ranging from 0.876 to 0.983. The genomic DNA fragments of about 1,434 bp consisted of two exons interrupted by an intron. Totally 24 SNPs, including 17 in the coding region and seven in the non-coding region, were detected by direct sequencing of 19 genomic samples. In exon 1, the coding SNPs (cSNPs) were only found in the disease-resistant specimens. The fluorescent real-time PCR analysis revealed that the expression of PtAK was detected in all the examined tissues with the highest expression in the muscle and the lowest in the eyestalk. The expression of PtAK after Vibrio alginolyticus injection was tested in haemocytes, showing that two peak values were 5.01-fold (at 3 h) and 3.60-fold (at 24 h) compared with the control values, respectively. The results suggested that AK might play an important role in the immune response in crabs.
精氨酸激酶（AK）是一种重要的磷酸转移酶，在无脊椎动物的能量代谢中起着关键作用。本文从游泳蟹（Portunus trituberculatus）眼柄 cDNA 文库中鉴定出 AK 的 cDNA（命名为 PtAK）。全长 cDNA 为 1479bp，包含一个 1074bp 的开放阅读框，编码 357 个氨基酸。成熟 PtAK 的估计分子质量为 40.30kDa，理论等电点为 6.18。氨基酸序列比对表明，PtAK 与其他虾和蟹 AK 具有非常高的相似性，相似度为 0.876 至 0.983。约 1434bp 的基因组 DNA 片段由两个外显子组成，中间被一个内含子打断。通过对 19 个基因组样本进行直接测序，共检测到 24 个 SNP，包括 17 个编码区和 7 个非编码区。在外显子 1 中，仅在抗病标本中发现了编码 SNP（cSNP）。荧光实时 PCR 分析显示，PtAK 在所有检测组织中均有表达，在肌肉中的表达最高，在眼柄中的表达最低。在血细胞中检测到 PtAK 在注射溶藻弧菌后的表达，与对照组相比，分别在 3 小时和 24 小时出现了两个峰值，分别为 5.01 倍和 3.60 倍。结果表明，AK 可能在蟹的免疫反应中发挥重要作用。
