ANNEXIN GENE STRUCTURES AND MOLECULAR EVOLUTIONARY GENETICS

Annexins provide an exemplary model for studying the pattern and proce ss of molecular evolution in multigene families. Their related gene st ructures, broad dispersal in eukaryotic genomes and abundant coding se quences permit a phylogenetic reconstruction of their genetic history. The emerging picture is one of prolific expansion by gene duplication to more than 27 paralogous subfamilies that have undergone steady seq uence divergence, speciation and differential selection. Homologous re combination via the common tetrad of internal repeats has, nevertheles s. strictly preserved this core structure for over 1200 million years. implying a basic functional role. The existence of multiple annexins with unique 5' coding and regulatory regions has facilitated their ada ptation to the varying ontogenetic and cell-specific needs of diverse organisms. Computational and cladistic sequence analyses have permitte d the determination of original gene duplication dates and mutation ra tes for the ten known vertebrate annexins. Molecular genetic and evolu tionary studies of annexins can help to define their structure-functio n relationships, elucidate their individual physiological roles and ul timately link them to hereditary phenotypes.