Reg2

Reg2 is a regulatory subunit of the protein phosphatase 1 (PP1) complex Glc7 in Saccharomyces cerevisiae and related fungi. It is part of the glucose signaling network and, together with Reg1, helps control the activity of the SNF1 kinase and the expression of glucose-repressed genes. Reg2 is closely related to Reg1, and the two proteins provide overlapping, partially redundant regulation of Glc7 activity in response to carbon sources.

Functionally, Reg2 binds Glc7 through a canonical PP1-binding motif and is thought to direct the phosphatase toward substrates involved in carbon metabolism, including SNF1. In high glucose conditions, Reg1–Glc7 dephosphorylates SNF1 to suppress SNF1-dependent transcription; Reg2 is believed to contribute to this repression and to modulate signaling under varying glucose levels. Genetic analyses suggest REG2 can partially compensate for loss of REG1, indicating overlapping roles in the regulation of glucose signaling.

Genetic and physiological studies indicate that mutations or deletion of REG2 can alter carbon source utilization, affecting growth on non-fermentable substrates and the regulation of Mig1-dependent genes. Expression of REG2 is responsive to carbon status, and its regulation integrates with other components of the glucose repression network.

Structurally, Reg2 is a small regulatory subunit that contains motifs common to PP1 regulatory partners, enabling binding to Glc7. It is thought to localize to the cytoplasm in complex with Glc7, mediating targeted dephosphorylation events.

Reg2 homologs have been identified in several budding yeasts and related fungi, suggesting a conserved role in glucose signaling across fungal species. See also: Protein phosphatase 1, Glc7, SNF1, glucose repression, REG1.