Transcriptional regulation by post-transcriptional modification--role of phosphorylation in Sp1 transcriptional activity.

Sp1 is a ubiquitously expressed transcription factor involved in the regulation of a large number of genes including housekeeping genes as well as actively regulated genes. Although Sp1 was discovered nearly three decades ago, its functional diversity is still not completely understood. One of the ways that make Sp1 versatile in transcriptional regulation is its post-transcriptional modification, which alters Sp1 structure in different cells and at different times. Compared to other types of modifications of the Sp1 protein, phosphorylation has been studied far more extensively. This review focuses on the inducers, pathways, enzymes, and biological effects of Sp1 phosphorylation. Recent data are beginning to reveal the biological significance and universal presence of Sp1 phosphorylation-related cell/molecular responses. Studies in this field provide a quick glance at how a simple chemical modification of a transcription factor could produce significant functional diversity of the protein.