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Marine Biotechnology

, Volume 3, Issue 4, pp 362–369 | Cite as

The Complete Primary Structure of Molluscan Shell Protein 1 (MSP-1), an Acidic Glycoprotein in the Shell Matrix of the Scallop Patinopecten yessoensis

  • Isao  Sarashina
  • Kazuyoshi  Endo

Abstract:

The complete primary structure of MSP-1, a major water-soluble glycoprotein in the foliated calcite shell layer of the scallop Patinopecten yessoensis, is reported. The full-length complementary DNA for MSP-1 isolated by polymerase chain reaction contained a sequence for a signal peptide of 20 amino acids followed by a polypeptide of 820 amino acids with calculated molecular mass of 74.5 kDa. The deduced amino acid sequence of MSP-1 includes a high proportion of Ser (32%), Gly (25%), and Asp (20%), and the predicted isoelectric point is 3.2; in these respects, MSP-1 is a typical acidic glycoprotein of mineralized tissues. A repeated modular structure characterizes MSP-1, with a sequence unit between 158 and 177 amino acids in length being repeated 4 times in tandem in the middle part of the protein. The repeated unit comprises 3 modules (SG, D, and K domains), each having a distinct amino acid composition and sequence. The SG domain is almost exclusively composed of Ser and Gly residues. The D domain is rich in Asp residues, potential N-glycosylation and phosphorylation sites. The K domain is rich in Gly residues and has a core of basic residues. The Asp residues are arranged more or less regularly in the D domains, exhibiting some repeated motifs such as Asp-Gly-Ser-Asp and Asp-Ser-Asp. Further, the 4 D domains indicate remarkable overall sequence similarities to each other. These observations suggest that the regular arrangements of COO groups in the D domain side chains may be important for specific control of crystal growth.

Key words: acidic shell protein, biomineralization, calcite, mollusks, MSP-1, primary structure. 

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Copyright information

© Springer-Verlag New York Inc. 2001

Authors and Affiliations

  • Isao  Sarashina
    • 1
  • Kazuyoshi  Endo
    • 1
  1. 1.Department of Earth and Planetary Sciences, University of Tokyo, Tokyo 113-0033, JapanJP

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