SAR1B : secretion associated Ras related GTPase 1B
Description
The SAR1B (secretion associated Ras related GTPase 1B) is a protein-coding gene located on chromosome 5.
The SAR1B gene provides instructions for making a protein that is produced in a variety of tissues. Most research involving the SAR1B protein has studied its role in the digestive tract.The SAR1B protein is needed for the transport of molecules called chylomicrons. During digestion, chylomicrons are formed within cells called enterocytes that line the small intestine and absorb nutrients. Chylomicrons are needed to absorb fat-soluble vitamins (vitamins K, E, and D) and carry fats and cholesterol from the small intestine into the bloodstream.Within enterocytes, SAR1B proteins help transport immature chylomicrons from a cell structure called the endoplasmic reticulum to another cell structure called the Golgi apparatus. Immature chylomicrons are processed within the Golgi apparatus, resulting in mature chylomicrons. These mature chylomicrons are then released from enterocytes into the bloodstream so the body can use the fats and fat-soluble vitamins they carry. Sufficient levels of fats, cholesterol, and vitamins are necessary for normal growth and development.In other tissues, such as the heart and other muscles, the SAR1B protein is likely involved in transporting calcium within cells.
SAR1B is a GTP-binding protein involved in the transport of molecules from the endoplasmic reticulum (ER) to the Golgi apparatus. It is activated by the guanine nucleotide exchange factor PREB. SAR1B plays a role in selecting protein cargo and assembling the COPII coat complex. It collaborates with the cargo receptor SURF4 to mediate the export of lipoproteins from the ER, thereby regulating lipoprotein delivery and maintaining lipid homeostasis.
SAR1B is also known as ANDD, CMRD, GTBPB, SARA2.
