A novel phosphorylated glycoprotein in the shell matrix of the oyster Crassostrea nippona.

We found a novel 52 kDa matrix glycoprotein MPP1 in the shell of Crassostrea nippona that was unusually acidic and heavily phosphorylated. Deduced from the nucleotide sequence of 1.9 kb cDNA, which is likely to encode MPP1 with high probability, the primary structure of this protein shows a modular structure characterized by repeat sequences rich in Asp, Ser and Gly.