Fold prediction and evolutionary analysis of the POZ domain: Structural and evolutionary relationship with the potassium channel tetramerization domain

Using iterative database searches, a statistically significant sequence similarity was detected between the POZ (<(po)under bar>xvirus and (z) under bar inc finger) domains found in a variety of proteins involved in animal transcription regulation, cytoskeleton organization, and development, and the tetramerization domain of animal potassium channels. Using the crystal structure of the Aplysia Shaker channel tetramerization domain as a template, the common structure of the POZ domain class was predicted. Examination of the structure resulted in the identification of several structural features and specific amino acid residues that may be involved in conserved protein-protein interactions mediated by the POZ domains as well as those that may contribute to the specificity of these interactions. Phylogenetic analysis of the POZ domains suggests that the common ancestor of the crown group eukaryotes already possessed this domain; POZ domains have undergone independent expansion in plants and in different animal lineages. (C) 1999 Academic Press.