Expression profile and structural divergence of novel human annexin 31

Systematic analysis of expressed sequence tags in dbEST yielded an expression profile of the ten known human annexins and led to the discovery of a novel subfamily expressed mainly in differentiating tissues. Full-length cDNAs encoded a 338-amino acid protein with less than 40% identity to other annexins, an atypical amino acid composition, and an insertion and deletion in internal repeat 3. The most striking feature was a complete ablation of all four type II calcium-binding sites in the conserved tetrad core. Annexin 31 thus constitutes a unique, natural probe for investigating the role of membrane binding in annexin function.