Involved in the regulation of nitrogen metabolism (PubMed:21265784, PubMed:23420616). Regulates the activity of its targets by protein-protein interaction in response to the nitrogen status of the cell (PubMed:24039236, PubMed:23069245). Increases the activity of the glutamine synthetase 3 in the presence of 2-oxoglutarate (PubMed:23069245). May regulate the activity of the ammonia channel Amt1 via direct interaction (PubMed:24039236). Homotrimer (PubMed:23069245). Interacts with the glutamine synthetase 3 (GS3) in the presence of 2-oxoglutarate (PubMed:23069245). Interacts with Amt1 after ammonium shock (PubMed:24039236). Highly expressed during ammonium starvation under nitrate-rich conditions. Uridylylated on Tyr-61. Deletion mutant shows growth deficiency in medium supplemented with nitrate. Belongs to the P(II) protein family.