cyclin box found in Saccharomyces cerevisiae G1/S-specific cyclins (ScCLNs) and similar proteins
ScCLNs, including ScCLN1-3, are essential for the control of the cell cycle at the G1/S (start) transition in Saccharomyces. ScCLN1 and ScCLN2 interact with the CDC28 protein kinase to form maturation promoting factor (MPF). ScCLN3 may be an upstream activator of the G1 cyclins that directly initiate G1/S transition. This family also includes Schizosaccharomyces pombe cyclin puc1, which contributes to negative regulation of the timing of sexual development in fission yeast, and functions at the transition between cycling and non-cycling cells. It interacts with protein kinase A. Members of this family contain one cyclin box. The cyclin box is a protein binding domain.