| Type: | Family | Name: | Cyclin T |
| Description: | Cyclins are eukaryotic proteins that play an active role in controlling nuclear cell division cycles [], and regulate cyclin dependent kinases (CDKs). Cyclins, together with the p34 (cdc2) or cdk2 kinases, form the Maturation Promoting Factor (MPF). There are two main groups of cyclins, G1/S cyclins, which are essential for the control of the cell cycle at the G1/S (start) transition, and G2/M cyclins, which are essential for the control of the cell cycle at the G2/M (mitosis) transition. G2/M cyclins accumulate steadily during G2 and are abruptly destroyed as cells exit from mitosis (at the end of the M-phase). In most species, there are multiple forms of G1 and G2 cyclins. For example, in vertebrates, there are two G2 cyclins, A and B, and at least three G1 cyclins, C, D, and E.Cyclin homologues have been found in various viruses, including Saimiriine herpesvirus 2(Herpesvirus saimiri) and Human herpesvirus 8(HHV-8) (Kaposi's sarcoma-associated herpesvirus). These viral homologues differ from their cellular counterparts in that the viral proteins have gained new functions and eliminated others to harness the cell and benefit the virus [].The cyclins in this entry are involved in the regulation of RNA polymerase II transcription []. Cyclin T partners with the cyclin dependent kinase Cdk9 and belongs to the P-TEFb complex. CyclinT/Cdk9 is responsible for the phosphorylation of the carboxyl-terminal domain (CTD) of the RNA Polymerase II, thus promoting general elongation []. T-type cyclins are also involved in cell differentiation and various pathological conditions including HIV replication and cancer [, ]. | Short Name: | Cyclin_T |
