CLONING OF THE XENOPUS-LAEVIS CDK2 PROMOTER AND FUNCTIONAL-ANALYSIS IN OOCYTES AND DURING EARLY DEVELOPMENT

CDK2 (cyclin-dependent kinase 2) is a serine/threonine kinase which is involved in regulating S-phase entry in higher eukaryotes. To investi gate the transcriptional control of this gene, a 13-kb Xenopus laevis genomic clone containing the 5' flanking sequences was isolated. A 2.7 -kb fragment containing the promoter region was sequenced and the tran scription start point (tsp) was determined by primer extension. Severa l putative regulatory elements, such as the E2F-binding site, Y box an d octamer-binding site, were localized in this region, but no TATA box was found. When fused to cat, a reporter gene encoding chloramphenico l acetyltransferase, the 5' flanking sequences were shown to function in oocytes and an enhancer activity was found in this region. During e arly embryogenesis, cdk2 promoter activity was tested and de novo tran scription was detected at the mid-blastula transition.