A crustacean Ca2+-binding protein with a glutamate-rich sequence promotes CaCO3 crystallization
A crustacean Ca2+-binding protein with a glutamate-rich sequence promotes CaCO3 crystallization
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DOI：
10.1042/bj20041052
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发表时间：
2004-11-15
影响因子：
4.1
通讯作者：
Watanabe, T
中科院分区：
文献类型：
--
作者：
Endo, H;Takagi, Y;Watanabe, T
DD4 mRNA在日本对虾（Penaeus japonicus）外骨骼附近的表皮中表达，特别是在脱毛后外骨骼发生钙化的时期。编码蛋白具有Ca2+结合位点，表明其参与外骨骼的钙化。在本研究中，在先前ORF的5'端发现了289个氨基酸的额外ORF（开放阅读框）。新鉴定的编码蛋白的部分包括一个约为。120个氨基酸高度丰富的谷氨酸残基，并含有一个或多个Ca2+结合位点。在免疫组织化学研究中，在外骨骼的管腔层的钙化区域检测到信号。细菌表达的部分蛋白片段在体外诱导CaCO3结晶。最后，一项逆转录pcr研究表明，这种表达仅限于蜕皮后时期的早期，即外骨骼显著钙化之前。这些观察结果表明，这种被命名为壳钙素（CCN）的编码蛋白可能通过诱导成核来促进外骨骼中CaCO3晶体的形成。
The DD4 mRNA of the penaeid prawn Penaeus japonicus was shown previously to be expressed in the epidermis adjacent to the exoskeleton specifically during the post-moult period, when calcification of the exoskeleton took place. The encoded protein possessed a Ca2+-binding site, suggesting its involvement in the calcification of the exoskeleton. In the present study, an additional ORF (open reading frame) of 289 amino acids was identified at the 5' end of the previous ORF. The newly identified part of the encoded protein included a region of approx. 120 amino acids that was highly rich in glutamate residues, and contained one or more Ca2+-binding sites. In an immunohistochemical study, signals were detected within calcified regions in the endocuticular layer of the exoskeleton. Bacterially expressed partial segments of the protein induced CaCO3 crystallization in vitro. Finally, a reverse transcription-PCR study showed that the expression was limited to an early part of the post-moult period, preceding significant calcification of the exoskeleton. These observations argue for the possibility that the encoded protein, renamed crustocalcin (CCN), promotes formation of CaCO3 crystals in the exoskeleton by inducing nucleation.