Sequence feature and expression profile of a tumor suppressor QM protein gene from hard clam Meretrix meretrix

The present study describes the molecular characterization and transcriptional features of a tumor suppressor QM protein gene, MmQM, in Meretrix meretrix. The full-length cDNA (819 bp) of MmQM consists of a 657 bp opening reading frame (ORF) encoding a 218 amino acid protein with a calculated molecular mass of 25.3 kDa and theoretical isoelectric point of 10.2. A ribosomal protein L10 signature, an SH3-binding motif, an antibiotic binding site, an amidation site and two protein kinase C phosphorylation sites were revealed from the MmQM sequence. Phylogenetic analysis showed that MmQM is clustered with previously identified mollusk QM proteins. MmQM mRNA transcripts were detectable in all of the examined tissues in a constitutive manner, and were significantly different from each other. After bacterial stimulation, the mRNA transcripts of MmQM in the hepatopancreas significantly increased. Hence, we conclude that MmQM could respond to pathogenic infections and it might play an important role in the innate immunity against microorganisms in the clam M. meretrix.