Sterol Regulatory Element-Binding Proteins (SREBPs) are transcription factors that bind to the sterol regulatory element DNA sequence TCACNCCAC. Mammalian SREBPs are encoded by the genes SREBF1 and SREBF2. SREBPs belong to the basic-helix-loop-helixleucine zipper class of transcription factors. Unactivated SREBPs are attached to the nuclear envelope and endoplasmic reticulum membranes. In cells with low levels of sterols, SREBPs are cleaved to a water soluble N-terminal domain that is translocated to the nucleus. These activated SREBPs then bind to specific sterol regulatory element DNA sequences, thus upregulating the synthesis of enzymes involved in sterol biosynthesis. Sterols in turn inhibit the cleavage of SREBPs and therefore synthesis of additional sterols is reduced through a negative feed back loop.
Mechanism of action
Beginning with the discovery of the Sterol Regulatory Element-Binding Proteins (SREBPs) in 1993, a productive combination of biochemistry, molecular biology and genetics, has brought to light the complex mechanisms by which animal cells maintain the proper levels of intracellular lipids (fats and oils) in the face of widely varying circumstances (lipid homeostasis).<ref... Read More