P-II indirectly controls the transcription of the glutamine synthetase gene (glnA). P-II prevents NR-II-catalyzed conversion of NR-I to NR-I-phosphate, the transcriptional activator of GlnA. When P-II is uridylylated to P-II-UMP, these events are reversed. When the ratio of Gln to 2-ketoglutarate decreases, P-II is uridylylated to P-II-UMP, which causes the deadenylation of glutamine synthetase by GlnE, so activating the enzyme. Homotrimer. Uridylylated/deuridylylated by GlnD. Belongs to the P(II) protein family.