Core component of multiple cullin-RING-based SCF (SKP1- CUL1-F-box) E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. As a scaffold protein may contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. The SCF complex associates with CDC34 as the E2 ubiquitin- conjugating enzyme. The functional specificity of the SCF complex depends on the type of F-box protein. SCF(CDC4) controls the G1- to-S phase transition; it directs ubiquitination of the phosphorylated CDK inhibitor SIC1 and of CDC6. SCF(CDC4) directs ubiquitination of GCN4. SCF(GRR1) directs ubiquitination of phosphorylated CLN1; CLN2 and GIC2. SCF(MET30) directs ubiquitination of MET4. SCF(DIA2) is specifically involved in the pheromone induced degradation of phosphorylated TEC1. SCF(MDM30) seems to direct ubiquitination of FZ01. Involved in the regulation of methionine biosynthesis genes. {ECO:0000269|PubMed:10213692; ECO:0000269|PubMed:16421250; ECO:0000269|PubMed:7813440; ECO:0000269|PubMed:9312054; ECO:0000269|PubMed:9346238; ECO:0000269|PubMed:9346239; ECO:0000269|PubMed:9499404; ECO:0000269|PubMed:9736614}.