Polyphosphoprotein from the adhesive pads of Mytilus edulis.
Achieving a satisfactory biochemical explanation for the opportunistic underwater adhesion of marine invertebrates such as mussels and barnacles requires a detailed characterization of proteins extracted from holdfast structures produced by these organisms. Mefp-5 is an adhesive protein derived from the foot of the common mussel, Mytilus edulis, and deposited into the byssal attachment pads. Purification and primary structure of mefp-5 was determined by peptide mapping and cDNA sequencing. The protein is 74 residues long and has a mass of about 9500 Da. Mefp-5 composition shows a strong amino acid bias: aromatic amino acids, lysine, and glycine represent 65 mol % of the composition. More than a third of all the residues in the protein are posttranslationally modified by hydroxylation or phosphorylation. The conversion of tyrosine to 3, 4-dihydroxyphenyl-L-alanine (DOPA) and serine to O-phosphoserine accounts for the hydroxylation and phosphorylation, respectively. Neither modification is complete since variations in the extent of phosphorylation and hydroxylation can be detected by mass spectrometry. More than 75% of the DOPA is adjacent to basic residues, e.g., Lys-DOPA and DOPA-Lys. Phosphoserine occurs in sequences strikingly reminiscent of acidic mineral-binding motifs that appear in statherin, osteopontin, and others. This may be an adaptation for adhesion to the most common substrata for mussels, i.e., calcareous materials.
Waite
J H
JH
Department of Cell Biology, Duke University, Durham, North Carolina 27706, USA. waite@lifesci.ucsb.edu
Qin
X
X
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001483:Base Sequence; D049872:Bivalvia / Q000737:chemistry* / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D020539:Sequence Analysis, Protein; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000596:Amino Acids; D018076:DNA, Complementary; D010750:Phosphoproteins; D011506:Proteins; C037403:adhesive protein, mussel