A carbonic anhydrase from the nacreous layer in oyster pearls

被引:478
作者
Miyamoto, H
Miyashita, T
Okushima, M
Nakano, S
Morita, T
Matsushiro, A
机构
[1] NISSIN FOOD PROD CO LTD,CENT RES INST,LAB PROT ENGN,KUSATSU,SHIGA 525,JAPAN
[2] OSAKA UNIV,MICROBIAL DIS RES INST,SUITA,OSAKA 565,JAPAN
关键词
D O I
10.1073/pnas.93.18.9657
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
It is believed that the polymorphism observed in calcium carbonate crystals, such as aragonite and calcite in mollusk shells, is controlled by organic matrix proteins secreted from the mantle epithelia. However, the fine structures of these proteins are still unknown, and to understand the molecular mechanisms of mineralization process, detailed structural analyses of the organic matrix proteins are essential, For this, we have carried out purification, characterization, and cDNA cloning of nacrein, which is a soluble organic matrix protein in the nacreous layer of oyster pearls, Northern blot analysis showed that the nacrein transcript was specifically expressed in mantle pallial, Analysis of the deduced amino acid sequence revealed that the protein contained two functional domains: one was a carbonic anhydrase and another was a Gly-Xaa-Asn (Xaa = Asp, Asn, or Glu) repeat domain; however, the carbonic anhydrase domain was split into two subdomains with insertion of the Gly-Xaa-Asn repeat domain between them, Our findings suggest that nacrein actually functions as a matrix protein whose repeated Gly-Xaa-Asn domain possibly binds calcium and as a carbonic anhydrase that catalyzes the HCO3- formation, thus participating in calcium carbonate crystal formation of the nacreous layer.
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页码:9657 / 9660
页数:4
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