GRR1

GRR1 is a gene in the budding yeast Saccharomyces cerevisiae that encodes the F-box protein Grr1p. Grr1p functions as a component of the SCF ubiquitin ligase complex, a multi-subunit E3 ligase consisting of Skp1, Cdc53 (a cullin), Rbx1, and an F-box protein. In this case, the SCF complex is referred to as SCF^Grr1, with Grr1p responsible for recognizing substrate proteins for ubiquitination and subsequent proteasomal degradation. Grr1p typically contains an N-terminal F-box motif that mediates binding to Skp1, and substrate-recognition regions that enable binding to phosphorylated targets.

GRR1 influences several cellular processes through degradation of distinct substrates. Notably, it targets the G1 cyclins Cln1 and Cln2, contributing to the regulation of the G1/S transition and cell cycle progression. In addition, Grr1p promotes the degradation of the transcriptional repressors Mth1 and Std1 in the presence of glucose, a process that relieves repression of hexose transporter (HXT) genes and supports metabolic adaptation to available carbon sources. The ability of SCF^Grr1 to modulate both cell cycle regulators and nutrient-responsive transcriptional regulators makes GRR1 an important node linking growth control to metabolic signaling.

GRR1 is part of a family of F-box proteins that recruit specific substrates to the SCF ubiquitin ligase, a mechanism widely used in eukaryotes to regulate protein turnover. In yeast, GRR1-like factors contribute to diverse regulatory networks, while GRR1 itself is studied for its roles in cell cycle control and glucose signaling.