Adhesive protein cDNA sequence of the mussel Mytilus coruscus and its evolutionary implications

cDNA encoding the adhesive protein of the mussel Mytilus coruscus (Mcfp1) was isolated. The coding region encoded 848 amino acids (a.a.) comprising the 20-a.a. signal peptide, the 21-a.a. nonrepetitive linker, and the 805-a.a. repetitive domain. Although the first 204 nucleotides and the 3'-untranslated region of Mcfp1 cDNA were homologous to corresponding parts of M. galloprovincialis adhesive protein (Mgfp1) cDNA, the other parts diverged. The representative repeat motif of the repetitive domain, YKPK(I/P)(S/T)YPP(T/S), was similar but slightly different from the repeat motif of Mgfp1. The codon usage patterns for the same amino acids were different in different positions of the decapeptide motif. Almost identical nucleotide sequences encoding the two to 13 repeats appeared several times in the repetitive region, which suggests that the adhesive protein genes of mussels have evolved through the duplication of these repeat units.