Sal k 4, a new allergen of Salsola kali, is profilin: a predictive value of conserved conformational regions in cross-reactivity with other plant-derived profilins.

The aim of this study was to investigate a new allergen of Salsola kali, Sal k 4, and to investigate the predictive value of the conserved conformational regions in cross-reactivity with other plant-derived profilins. The Sal k 4-coding sequence was cloned, expressed, and purified by one-step Ni2+ affinity chromatography to recover high-purity target protein. We assessed cross-reactivity and predicted conserved conformational regions among rSal k 4 and other plant-derived profilins. Immunodetection and inhibition assays using 30 individual sera from S. kali allergic patients indicated that purified rSal k 4 might be the same as that in the crude extract. The results of inhibition assays among rSal k 4 and other plant-derived profilins were in accordance with the homology of the predicted conserved conformational regions. Amino acid sequence homology analysis showed that a high degree of IgE cross-reactivity among plant-derived profilins might depend on the predicted conserved conformational regions.