Reference work entry
Specificity protein 1 (Sp1) is a member of the so-called Sp/Krüppel-like factor family that was first identified as a transcription factor binding to a GC-rich region of the SV40 early promoter region (Dynan and Tjian 1983). Unlike other members of this family, Sp1 is ubiquitously expressed, and this reflects its vital role in cell function. Sp1 structure and function are well characterized, with the transcription factor comprising 785 amino acid residues (Fig. 1) and contributing to the basal regulation of multiple targets including house-keeping genes. Sp1 generally regulates TATA-less gene promoters (Wierstra 2008; Vizcaíno et al. 2015). However, Sp1 can also augment activity of TATA-containing promoters via TATA-box binding protein (Vizcaíno et al. 2015). Sp1 typically binds double-stranded DNA containing GC-rich sequences via zinc finger motifs, thereafter recruiting the general transcription machinery to the target gene...
© Springer International Publishing AG 2018