Abstract
Arabidopsis thaliana has a small family of pseudo-response regulators (PRRs), consisting of five members, among which PRR1/TOC1 is believed to be a clock component. PRRs are nuclear-localized proteins, otherwise nothing is known about their molecular function(s). In their amino acid sequences, they share an intriguing structural design, in which each contains an N-terminal pseudo-receiver domain, followed by a common C-terminal CCT motif. To gain insight into the function(s) of the PRR family of clock components by employing the PRR1 and PRR5 genes, here we constructed a set of transgenic plants, each of which was designed so as to constitutively express each structural domain separately (e.g., pseudo-receiver domain, CCT motif). These transgenic plants were extensively characterized with regard to the clock-associated phenotypes (e.g., rhythm, flowering, photo-sensitivity), and these results will be discussed with reference to the current idea of the clock-associated functions of PRRs.
