BACKGROUND Cyclins are highly conserved proteins that activate cyclin-dependent kinases (CDKs) to regulate the cell cycle, transcription and other cellular processes. There are several different cyclins that are active in different parts of the cell cycle and that cause the Cdk to phosphorylate different substrates. There are also several "orphan" cyclins for which no Cdk partner has been identified. For example, cyclin F is an orphan cyclin that is essential for G2/M transition. These cyclins can heterodimerize with specific catalytic subunits, Cdks, to form holoenzymes. Some substrates of these holoenzymes, which are inactivated upon phosphorylation, are pRB and the related proteins, p130 and p107. It is thought that phosphorylation and inactivation of pRB leads to progression through the restriction point.1 The ability of the cyclin/Cdk holoenzymes to phosphorylate pRB is inhibited by a family of small molecular weight proteins, known as cyclin-dependent kinase inhibitors (CKIs). The concentration of cellular cyclins varies in a cyclical fashion during the cell cycle; they are produced or degraded as needed in order to drive the cell through the different stages of the cell cycle. When concentrations in the cell are low, cyclins dissociate from Cdk, thus inhibiting enzymatic activity.2 Cyclins themselves have no enzymatic activity.
There are two subtypes of cyclin A, cyclin A1 and cyclin A2. Among the cyclins, cyclin A2 is unique in that it regulates progression through two critical transitions: cyclin A2 complexed with cdk2 is essential for the G1/S transition and cyclin A2/cdk1 promotes entry into mitosis.3 In contrast, meiotic cells (oocytes and spermatocytes) express cyclin A1. Cyclin A1 is proposed to regulate M phase in the meiotic cell cycle. Several lines of evidence have also implicated cyclin A in carcinogenesis.4
1. Xiong, Y. & beach, D. Curr. Biol. 1:362-4, 1991
2. Pestell, R.G. et al: Endocrinol. Rev. 20:501-34, 1999
3. Chaudhry, H.W. et al: J. Biol. Chem. 279:35858-66, 2004
4. Payraudeau, V. et al: Mol. Cell. Endocrinol. 143:107-116, 1998
Products are for research use only. They are not intended for human, animal, or diagnostic applications.
|Synthesized peptide derived from human Cyclin A|
Species & predicted
reactivity ( ):
|Human, Mouse, Rat|
Weight of protein:
|52 KDa |
|Detects endogenous Cyclin A2 proteins without cross-reactivity with other family members.|
Store at -20°C, 4°C for frequent use. Avoid repeated freeze-thaw cycles.
*Optimal working dilutions must be determined by end user.