Phytochrome moves to the nucleus Phytochrome moves to

Phytochrome moves to the nucleus

Phytochrome moves to the nucleus In some cases phytochrome itself moves to the nucleus in a light-dependent manner. The Phy. B moves to the nucleus in the Pfr form only, and transport is slow (several hrs). The Phy. A can move in the Pfr or the Pr form, and transport is rapid (about 15 min). Transport of Phy. B-GFP is promoted by red light and inhibited by far-red light. Transport of Phy. A-GFP is maximized under continuous far-red light. Nuclear translocation of Phy. B is under circadian control.

What Happens when Pfr moves to the nucleus? PIF 3 (phytochrome interacting fator 3)

Phytochrome Acts though Multiple Signal Transduction Pathways.

G-protein may function downstream of phtochrome. (microinjection experiment) After G-Protein, there at least two branching pathways. 1) Gene and chloroplast development : require Ca 2+ and calmodulin 2) Anthocyanin synthesis : is independent on Ca 2+ 3) c. GMP may serve as a second messenger in phytochrome action. Phytochrome is now known to be a protein kinase. One potential target is a cytosolic protein termed PKS 1 that can accept a P from Phy. A. OX of PKS 1 suggest that is may function to negatively regulate PHy. B mediated events

NDPK 2 is another protein kinase associated with phytochrome. Iys kinase activity is increaseb about 2 -fold when Phy. A is bound in the Pfr form.

Thanks for your attention