Phytochromes are Pr-ipatetic kinases.

A series of new studies reveal how the red/far-red light photoreceptors called phytochromes act. Phytochrome A and phytochrome B each move to the nucleus when activated by light, and phytochrome A is a kinase. Phytochrome-interacting proteins provide candidate signal transduction components and a recent physiological study suggests how phyA may mediate responses to far-red light. Regulation of phytochrome nuclear localization and kinase activities creates multiple phytochrome species, which may each have different regulatory activities.