Cell cycle regulation, model of suc1 protein

Model of crystal structure of the protein suc1, which helps regulate the cell cycle. The 3 bound zinc ions are drawn as pink spheres. Suc1's exact function is not known, but it binds to a CDK (cyclin-dependent kinase), so presumably modifies its activity, localisation or substrate specificity. Structural features shown here can be probed by site-directed mutagenesis to help determine suc1's role in cell cycle regulation.