Precursor of the transcription factor form (Processed sterol regulatory element-binding protein 2), which is embedded in the endoplasmic reticulum membrane . Low sterol concentrations promote processing of this form, releasing the transcription factor form that translocates into the nucleus and activates transcription of genes involved in cholesterol biosynthesis .
Key transcription factor that regulates expression of genes involved in cholesterol biosynthesis (, ). Binds to the sterol regulatory element 1 (SRE-1) (5'-ATCACCCCAC-3'). Has dual sequence specificity binding to both an E-box motif (5'-ATCACGTGA-3') and to SRE-1 (5'-ATCACCCCAC-3') (, ). Regulates transcription of genes related to cholesterol synthesis pathway (, ).
Subcellular locations: Endoplasmic reticulum membrane, Golgi apparatus membrane, Cytoplasmic vesicle, COPII-coated vesicle membrane
At high sterol concentrations, the SCAP-SREBP is retained in the endoplasmic reticulum . Low sterol concentrations promote recruitment into COPII-coated vesicles and transport of the SCAP-SREBP to the Golgi, where it is processed .
Subcellular locations: Nucleus
Transported into the nucleus with the help of importin-beta. Dimerization of the bHLH domain is a prerequisite for importin beta-dependent nuclear import.
Ubiquitously expressed in adult and fetal tissues.