OSBP
Description
The OSBP (oxysterol binding protein) is a protein-coding gene located on chromosome 11.
OSBP is an intracellular protein identified as a cytosolic 25-hydroxycholesterol-binding protein. It acts as a lipid transfer protein, controlling cholesterol/PI4P exchange at ER-Golgi membrane contact sites. OSBP regulates ER-Golgi membrane contact sites formation by bridging ER and Golgi membranes together. 25-hydroxycholesterol inhibits this exchange. OSBP also plays a role as a sterol-regulated scaffolding protein for several cytosolic reactions, including the phosphorylation of ERK 1/2. OSBP expression levels in transgenic mice affect liver and serum TG levels. OSBP is thought to be an essential scaffolding compound of the protein complex that regulates the activation state of the ERK protein and acts as a sterol-dependant scaffold for the JAK2 and STAT3 proteins.
OSBP, also known as oxysterol-binding protein 1, is a lipid transporter involved in lipid countertransport between the Golgi complex and membranes of the endoplasmic reticulum. It specifically exchanges sterol with phosphatidylinositol 4-phosphate (PI4P), delivering sterol to the Golgi in exchange for PI4P, which is degraded by the SAC1/SACM1L phosphatase in the endoplasmic reticulum. OSBP binds cholesterol and a range of oxysterols including 25-hydroxycholesterol. Cholesterol binding promotes the formation of a complex with PP2A and a tyrosine phosphatase which dephosphorylates ERK1/2, whereas 25-hydroxycholesterol causes its disassembly. OSBP regulates cholesterol efflux by decreasing ABCA1 stability.
OSBP is also known as OSBP1.
Associated Diseases
- hemoglobin D disease
- dominant beta-thalassemia
- hemoglobin C-beta-thalassemia syndrome
- hemoglobin E disease
- hemoglobin H disease
- beta-thalassemia-X-linked thrombocytopenia syndrome
- hereditary persistence of fetal hemoglobin-sickle cell disease syndrome
- delta-beta-thalassemia
- alpha-thalassemia-myelodysplastic syndrome
- hemoglobin E-beta-thalassemia syndrome
- cancer
