What type of proteins are cyclins classified as?

Cyclins are classified as regulatory proteins because they play a crucial role in controlling the cell cycle. They function by activating cyclin-dependent kinases (CDKs), which are essential for the progression of cells through different phases of the cell cycle, such as the transition from G1 to S phase or from G2 to M phase. The concentration of cyclins fluctuates during the cycle, allowing for the precise regulation of cell division and ensuring that the events of the cell cycle occur in the correct order and at the right time. This regulatory mechanism is vital for normal cell function and for preventing uncontrolled cell growth, which can lead to cancer.