PREB
Function
Guanine nucleotide exchange factor (GEF) that regulates the assembly of the coat protein complex II/COPII in endoplasmic reticulum (ER) to Golgi vesicle-mediated transport. Selectively activates SAR1A and SAR1B by promoting the exchange of guanosine diphosphate (GDP) for guanosine triphosphate (GTP) in these small GTPases (PubMed:32358066). In their activated GTP-bound state, SAR1A and SAR1B insert into the membrane of the endoplasmic reticulum where they recruit the remainder of the coat protein complex II/COPII which is responsible for both the sorting of proteins and the deformation and budding of membranes into vesicles destined to the Golgi (PubMed:32358066).
Was first identified based on its probable role in the regulation of pituitary gene transcription. Binds to the prolactin gene (PRL) promoter and seems to activate transcription.
Tissue Specificity
Ubiquitous.
Cellular localization
- Endoplasmic reticulum membrane
- Single-pass membrane protein
- Nucleus
- Concentrates at endoplasmic reticulum exit sites (ERES), also known as transitional endoplasmic reticulum (tER).
Alternative names
SEC12, PREB, Guanine nucleotide-exchange factor SEC12, Prolactin regulatory element-binding protein