Characterization of p26olf, a novel calcium-binding protein in the frog olfactory epithelium

We have previously shown that p26olf is a novel S100-like Ca2+-binding prot ein in the frog olfactory epithelium, In this paper, we characterized the C a2+ binding property of p26olf, examined the precise localization in the fr og olfactory epithelium, and searched for the possible target proteins of p 26olf. By flow dialysis experiments using Ca-45, p26olf was suggested to bi nd similar to 4 Ca2+ Circular dichroism measurement showed that binding of Ca2+ to p26olf induces an increase in the apparent content of both alpha-he lix and beta-sheet with an apparent K-d value of 2.4 mu M. Electron microsc opic observation disclosed p26olf immunoreactivity in the cilia, dendritic knob, and dendrite of olfactory receptor cells. Blot overlay analysis and a ffinity purification of p26olf-binding proteins showed that p26olf binds to a frog beta-adrenergic receptor kinase-like protein in a Ca2+-dependent ma nner. These results suggested that p26olf has some roles in the olfactory t ransduction or adaptation.