CHARACTERIZATION OF HUMAN CYCLIN G(1) AND G(2) - DNA-DAMAGE INDUCIBLEGENES

Several genes have been identified as targets for transcriptional acti vation by the p53 tumour suppressor protein. Rodent cyclin G was previ ously identified as a p53 responsive gene and in order to assess the r ole played by cyclin G as a mediator of p53 function in humans cells w e have isolated full length human cyclin G(1) and identified a related gene designated cyclin G(2). Both human G-cyclins are induced by the DNA damaging agent actinomycin-D and although the induction of cyclin G(1) is clearly p53 dependent, activation of cyclin G(2) expression wa s observed in the absence of p53. Based on sequence similarity, the G- cyclins and the recently identified cyclin I form a distinct sub-group within the larger cyclin family, possibly reflecting some degree of f unctional similarity.