Fig. 2.

Molecular structures of NLPs in plants. NLPs contain three domains: nitrate-responsive domain (NRD), RWP-RK, and Phox and Bem1 (PB1). The site S205 in NRD is an essential phosphorylation site for the nuclear retention of NLPs. RWP-RK contains two α-folds (i.e., α1 and α2) and an amphipathic leucine zipper (ALZ), and they are involved in DNA binding. The PB1 domain contains both type I and type II, and it facilitates protein–protein interactions. Type I comprises β1 (including a K residue), β2, and α1, whereas β3, β4, α2, and β5 are located in type II region. K863, D909, D911, and E913 are required for the interactions by NLPs