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Originally published in Science Express on 13 August 2009
Science 11 September 2009:
Vol. 325. no. 5946, pp. 1388 - 1390
DOI: 10.1126/science.1173793
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Reports

An Acidic Matrix Protein, Pif, Is a Key Macromolecule for Nacre Formation

Michio Suzuki,1 Kazuko Saruwatari,2 Toshihiro Kogure,2 Yuya Yamamoto,3 Tatsuya Nishimura,3 Takashi Kato,3 Hiromichi Nagasawa1,*

The mollusk shell is a hard tissue consisting of calcium carbonate crystals and an organic matrix. The nacre of the shell is characterized by a stacked compartment structure with a uniformly oriented c axis of aragonite crystals in each compartment. Using a calcium carbonate–binding assay, we identified an acidic matrix protein, Pif, in the pearl oyster Pinctada fucata that specifically binds to aragonite crystals. The Pif complementary DNA (cDNA) encoded a precursor protein, which was posttranslationally cleaved to produce Pif 97 and Pif 80. The results from immunolocalization, a knockdown experiment that used RNA interference, and in vitro calcium carbonate crystallization studies strongly indicate that Pif regulates nacre formation.

1 Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
2 Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
3 Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.

* To whom correspondence should be addressed. E-mail: anagahi{at}mail.ecc.u-tokyo.ac.jp

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Molecular Basis of Nacre Formation.
N. Kroger (2009)
Science 325, 1351-1352
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