CTF5A NEW TRANSCRIPTIONAL ACTIVATOR OF THE NFI CTF FAMILY/

MFI/CTF is a family of polypeptides involved in stimulating the initia tion of adenovirus DNA replication and the activation of transcription driven by RNA polymerase II, Several naturally occurring NFI/CTF vari ants display distinctive transactivation activities in vivo. To define more precisely the role of the NFI/CTF family in regulating gene expr ession, we cloned the splice variant CTF5, analyzed transcriptional ac tivation patterns in a yeast transcription assay, and compared it with other CTF proteins, CTF5, which lacks exons 9 and 10 including a CTD- like motif essential for transcriptional activation by full-length CTF 1, enhances transcription to a greater extent than CTF1, In addition, CTF5 is even more active than CTF7, which lacks exons 7-9, These findi ngs indicate that CTF proteins formed by differential splicing display a much broader range of transcriptional activities as observed previo usly.