Sino Biological offers a comprehensive set of tools for cyclin related studies, including recombinant proteins, antibodies (rabbit mAbs, mouse mAbs and rabbit pAbs), ELISA kits and ORF cDNA clones.
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Cyclins are a group of proteins that that control the progression of cells through the cell cycle by activating cyclin-dependent kinase (CDK) enzymes. Cyclins and clyclin-dependent kinases were discovered by Leland H. Hartwell, R. Timothy Hunt, and Paul M. Nurse, who thus won the 2001 Nobel Prize in Physiology or Medicine. Hunt and his colleagues discovered that the concentration of cyclins varied in a cyclical fashion during the cell cycle; they were produced or degraded as needed in order to drive the cell through the different stages of the cell cycle. Cyclin’s discovery led to a model of the autonomous oscillator that drove the cell cycle of early embryonic cells.
Each cyclin associates with one or two cyclin-dependent kinases, and most cyclin-dependent kinases associate with one or two cyclins. Formation of cyclin-CDK complex results in activation of the CDK active site. Early work in frog and invertebrate embryos suggested that cell cycle events are triggered by the activity of a biochemical oscillator centered on cyclin-CDK complexes. The cyclin/CDK complexes induce two processes, duplication of centrosomes and DNA during interphase, and mitosis. The roles of individual cyclins were tested by adding recombinant proteins to cyclin- biologidepleted extracts. Cyclin E supports DNA replication and centrosome duplication, cyclin A supports both of these processes and mitosis, and cyclin B supports mitosis alone. In the cell cycle, Cyclin D/CDK4, Cyclin D/CDK6, and Cyclin E/CDK2 regulate transition from G1 to S phase; Cyclin A/CDK2 is active in S phase; Cyclin B/CDK1 regulates progression from G2 to M phase.
The degradation of cyclins is through ubiquitin-proteasome pathway. Cyclins are targeted to the proteasome by the addition of a chain of ubiquitins. G1 cyclins are ubiquitinated by the SCF complex, while mitotic cyclins are ubiquitinated by the anaphase-promoting complex (APC).