Nuclear F-box protein and subunit of SCF-Met30 Ub-ligase complex; controls the cell cycle, sulfur metabolism, and methionine biosynthesis as part of SCF-Met30 Ub-ligase complex; sulfide-sensor that represses activity of Met4p in response to sulfur abundance; involved in turnover of Cdk-inhibitory kinase Swe1p; Cdc48p catalyzes dissociation of Met30p from SCF complex in response to cadmium stress; contains WD40 repeat region with cysteines that sense sulfur availability