p23 and HSP20/α‐crystallin proteins define a conserved sequence domain present in other eukaryotic protein families

Abstract

We identified families of proteins characterized by the presence of a domain similar to human p23 protein, which include proteins such as Sgt1, involved in the yeast kinetochore assembly; melusin, involved in specific interactions with the cytoplasmic integrin β1 domain; Rar1, related to pathogenic resistance in plants, and to development in animals; B5+B5R flavo‐hemo cytochrome NAD(P)H oxidoreductase type B in humans and mice; and NudC, involved in nucleus migration during mitosis. We also found that p23 and the HSP20/α‐crystallin family of heat shock proteins, which share the same three‐dimensional folding, show a pattern of conserved residues that points to a common origin in the evolution of both protein domains. The p23 and HSP20/α‐crystallin phylogenetic relationship and their similar role in chaperone activity suggest a common function, probably involving protein–protein interaction, for those proteins containing p23‐like domains.