Molecular cloning and expression analysis of BMP7b from Pinctada fucata

In order to understand the role of BMP in biomineralization process in mollusca, a BMP7 homolog in Pinctada fucata named BMP7b was cloned in this study. The full length of BMP7b was 2 464 bp, including an open reading frame (ORF) of 1 194 bp which encoded 397 amino acids. The protein sequence included a signal peptide (1–26 aa), a pro-domain (25–240 aa) and a TGF-β domain (299–396 aa). No transmembrane domain was detected. BMP7b was expressed in all kinds of tissues and was higher expressed in gill and mantle, but lower in intestine and hepatopancreas. The BMP7b expression level at larva stage was much higher than that in other periods. In shell notch experiment, BMP7b showed increasing expression level after 24 h. These results indicate that BMP7b may play an important role in process of shell formation and repairment.