Transcription factor activity of STAT proteins: structural requirements and regulation by phosphorylation and interacting proteins

The seven mammalian members of the signal transducer and activator of trans cription (STAT) family share a common core structure which reflects their s hared mechanism of activation, dimerization, and DNA binding. By contrast, the STAT C termini containing the sequences required for transcriptional ac tivation are much less homologous, suggesting different ways by which indiv idual STATs activate their target genes. This paper describes several impor tant discoveries linked to mechanistic aspects of STAT transcription factor function. These include regulated serine phosphorylation of the transactiv ating domain, promoter-dependent interactions of STATs with each other, or of STATs with other transcription factors, and with transcriptional co-acti vators. The basis, background, and implications of these molecular events w ill be summarized and discussed.