Expression pattern and preliminary functional analysis of human CREB4 gene.

cAMP response element-binding (CREB) proteins are a family of mammalian transcription activators that mediate cAMP and calcium-dependent gene expression through the cAMP response element (CRE). CREB4 is a novel member of the human CREB family. RT-PCR showed CREB4 transcripts were found in lung carcinoma LX-1, colon adenocarcinoma CX-1, prastatic adenocarcinoma PC-3, colon carcinoma G1-112, and pancreatic adenocarcinoma G1-103. Constructing CREB4 and CREB(215-395aa) fusion protein with the entire prokaryotic LexA protein respectively disclosed that CREB4 protein functioned as a transcription activator and its N-terminal accounted for the activation ability. Furthermore,a fusion protein of GFP and full-length CREB4 was localized in cytoplasm,whereas the fusion protein of GFP and a deletion mutant lacking the C-terminal putative transmembrane domain was translocated in nucleus. Our results suggested that putative transmembrane domain of CREB4 protein was associated with modulation of its function for the transcriptional activation.