The amino‐acid sequence of the abalone ( Haliotis laevigata ) nacre protein perlucin

Abstract

Perlucin isolated from abalone nacre consists of 155 amino acids including a glycosylated asparagine. The sequence of the first 130 amino acids shows a high similarity to the C‐type carbohydrate‐recognition domains of asialoglycoprotein receptors and other members of the group of C‐type lectins but also a weaker similarity to related proteins without carbohydrate‐binding activity. This C‐type module is followed by a short C‐terminal domain containing two almost identical sequence repeats with a length of 10 amino acids. Solid phase assays show a divalent metal ion‐dependent binding of perlucin to (neo)glycoproteins containing d ‐galactose or d ‐mannose/ d ‐glucose indicating that perlucin is a functional C‐type lectin with broad carbohydrate‐binding specificity. Our results also indicate that it may be difficult to predict carbohydrate‐binding specificity and the occurrence of alternative binding configurations by amino‐acid sequence comparisons and homology modeling.