Pleiotropic regulator of glucose, stress and hormone responses. Also regulates cytochrome P450 CYP90A1/CPD. Coordinates the expression of hormone- and stress-related genes and genes related to cell wall modification and growth, leading to altered sugar-dependent growth and developmental responses. Component of the MAC complex that probably regulates defense responses through transcriptional control and thereby is essential for plant innate immunity. By suppressing the expression of several (1)O(2)-responsive genes, PRL1 seems to play a major role in modulating responses of plants to environmental changes by interconnecting (1)O(2)-mediated retrograde signaling with other signaling pathways. Acts as negative regulator of SNF1-related protein kinases AKIN10 and AKIN11 via the inhibition of their interaction with SKP1/ASK1. Component of the CUL4-RBX1-DDB1-PRL1 E3 ubiquitin-protein ligase complex, PRL1 may function as the substrate recognition module within this complex, leading to the AKIN10 degradation. Protein modification; protein ubiquitination. Component of the multiprotein assembly MOS4-associated complex (MAC) at least composed of MOS4, CDC5, PRL1 and PRP19 (PubMed:17575050, PubMed:19629177). Interacts with CDC5 (PubMed:17575050). Component of the CUL4-RBX1-DDB1-PRL1 E3 ubiquitin-protein ligase complex. Interacts with DDB1A through its DWD motif (PubMed:18223036). Interacts with AKIN10, AKIN11 and PIPC (PubMed:10220464). Interacts with KAP2 (PubMed:9765207). The DWD box is required for interaction with DDB1A. Hypersensitivity to glucose and sucrose. Enhanced sensitivity of plants to stress and to growth hormones including cytokinin, ethylene, abscisic acid, and auxin. Accumulation of sugars and starch in leaves, and root elongation. Cell elongation defects. Enhanced susceptibility to virulent and avirulent pathogens. Belongs to the WD repeat PRL1/PRL2 family.