Tyrosinase localization in mollusc shells

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 146; no. 2; pp. 207 - 214
• Main Authors: Nagai, Kouhei, Yano, Masato, Morimoto, Koichi, Miyamoto, Hiroshi
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01-02-2007
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Binding Sites; Blotting, Northern; Calcification; Carrier Proteins - chemistry; Carrier Proteins - genetics; Carrier Proteins - metabolism; Copper - metabolism; DNA, Complementary - chemistry; DNA, Complementary - genetics; Electrophoresis, Polyacrylamide Gel; Gene Expression Profiling; Gene Expression Regulation, Enzymologic; Isoenzymes - chemistry; Isoenzymes - genetics; Isoenzymes - metabolism; Mantle; Marine; Molecular Sequence Data; Mollusc; Monophenol Monooxygenase - chemistry; Monophenol Monooxygenase - genetics; Monophenol Monooxygenase - metabolism; Pearl oyster; Phylogeny; Pigmentation; Pinctada - enzymology; Pinctada - genetics; Pinctada fucata; Prismatic layer; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Shell; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tyrosinase; Shell; Pearl oyster; Calcification; Prismatic layer; Mantle; Mollusc; Pigmentation; Tyrosinase
• ISSN: 1096-4959; 1879-1107
• DOI: 10.1016/j.cbpb.2006.10.105

In molluscan shellfish, pigmentation is frequently observed in the calcified shell, but the molecular basis of this process is not understood. Here, we report two tyrosinase proteins (Pfty1 and Pfty2) found in the prismatic shell layer of the pearl oyster
Pinctada fucata; this layer is recognized as the pigmented region in
P. fucata. The protein sequences were deduced from the corresponding cDNAs and confirmed by MALDI-TOF/TOF analysis. The sequences suggest that both tyrosinases have two copper-binding sites in similar N-terminal domains that are homologous to tyrosinases of cephalopods and hemocyanins of gastropods. In turn, this suggests that bivalve tyrosinases are evolved from a common ancestral copper-binding protein in the mollusc. Pfty1 and Pfty2 were specifically expressed in the mantle, and their expression in the mantle is different from each other, suggesting that these tyrosinases have distinctive roles in melanogenesis in shells.