Abstract
In Arabidopsis, blue light (BL) receptors phototropin1 (phot1) and phot2 mediate phototropic response. NPH3 is an essential signal transducer in the induction of phototropic response by phot1 and phot2. Whereas expression of NPH3 protein does not change in response to in vivo irradiation, molecular size changes in response to irradiation with blue or red light. But biochemical function of NPH3 has been not clear. Here we analyzed protein expression in seedlings irradiated with various wavelength of light involved in phototropic response. We demonstrate that NPH3 is modificated by red light irradiation or dark-grown, and de-modificated by BL irradiation. The de-modification of NPH3 is sensitive to BL, and depends on BL intensity. We also show that the phot1 is essential to de-modification of NPH3, but not phot2. These results suggested that function of de-modification of NPH3 is essential to induce phototropic response by phot1.
