Abstract
Phototropism of Arabidopsis seedlings in response to blue light source is initiated by phototropin1 (phot1) and phot2, blue light receptor kinases. Previous studies have shown that NPH3 and RPT2 are signal transducer in phototropin signaling. However, only few attempts have been made at biochemical analysis of NPH3 and RPT2. Here, we show that NPH3 in seedlings in dark or red light condition is phosphorylated in vivo, and NPH3 is de-phosphorylated under blue light. Accumulation of RPT2 in blue light condition was indicated. Both NPH3 de-phosphorylaion and accumulation of RPT2 which are induced by blue light are mediated by phot1 but not phot2. NPH3 and RPT2 make a complex depended on blue light. While we demonstrated cellular and subcellular localization of RPT2 in seedlings irradiated with blue light. On the basis of these results, we discuss the roles of NPH3 and RPT2 in the phot1 signaling pathways.
