Specificity Protein 4 (SP4)

Transcriptional regulation is exerted through protein factors that bind to distinct DNA elements in the vicinity of target genes. Many control elements are recognized by different members of transcription factor families, opening combinatorial possibilities of the regulatory interactions.SP4 is abundantly expressed as a 7.5-kb message in brain, but barely detectable in other human cell lines. SP4 is an activator protein like SP1. However, in contrast to SP1, they found that SP4 is not able to act synergistically through adjacent binding sites.The chromosomal localization was further refined by fluorescence in situ hybridization to 7p15. The previous assignment of the SP1 gene to 12q13, together with the assignment of the SP4 gene to 7p15, increases the number of known paralogous relationships between human chromosomes 7 and 12.