The cyclin family of budding yeast: abundant use of a good idea

Cyclins are highly conserved proteins that activate cyclin-dependent kinases (CDKs) to regulate the cell cycle, transcription and other cellular processes. The completion of tbe genome sequence of tbe budding yeast Saccharomyces cerevisiae allows an appraisal of the functions of the entire complement of cyclins in a eukaryotic organism. The cyclin family of budding yeast is reviewed from a functional perspective with an emphasis on what genetic and biochemical experiments have revealed about cyclin-CDK substrates.