Abstract
From the soluble fraction of tobacco callus, we characterized a cytokinin-binding protein 2 (CBP2), which has 26kDa, Kd=1.06X10-6 M and high homology with osmotin-like protein (OLP), a stress protein (Plant Cell Physiol.41:148-157, 2000). CBP2 and OLP show same
structural feature in SDS-PAGE and Western blot analyses (B.B.B.65:2806-2810, 2001).
Under these evidences, after cloning of CBP2, AtOLP of Arabidopsis thaliana was retrieved as a high homolog (61.2 %). Plasmid of over-expression of AtOLP was formed by directing 35S promoter of cauliflower mosaic virus and the transformant of Arabidopsis was formed via vinary vector. The elongation of root in seedlings of this transformant (T2) was tested against various concentrations of cytokinin (BA), and it was strongly inhibited by 10-7 M BA.
This phenomenon suggests that CBP2 exists not only in tobacco, but also in Arabidopsis and has the function as a cytokinin receptor.
