Cyclins

1. Cyclins Cyclin is a type of protein that expresses, accumulates, and decomposes in a cell cycle, and it interacts with cyclin-dependent kinases to affect cell cycle function. Cyclin has involved in cell cycle-regulated proteins, and its concentration is cyclic and cyclical in the cell cycle. Depending on the stage of the cell cycle, sometimes the concentration is as high as several thousand times, and sometimes it drops to zero. As a regulatory subunit, cyclin binds to and activates cyclin-dependent protein kinases. Different cyclins are expressed in different periods in the cell cycle. In mammalian cells, cyclin A begins to express and gradually accumulate in the early G1 phase, reaching the G1/S junction, and the content reaches the maximum and remains in the G2/M phase. Cyclin B is expressed from the late G1 phase and gradually accumulates. It reaches the maximum in the late G2 phase and maintains to the mid-stage of the M phase, and then rapidly degrades. Cyclin D, which is a G1 phase cyclin, is continuously expressed in the cell cycle, while cyclin E begins to express and gradually accumulate in the late M phase and early G1 phase, reaching the maximum in the late G1 phase, and then gradually reaching its maximum content, declining until the late G2 phase. Cyclin plays an important role in the regulation of the cell cycle. Studying the mechanism of cyclins has great significance for the treatment of cancer.