Sar1
Encyclopedia
SAR1A or Sar1 is a protein involved in membrane trafficking. It is a GTPase
found in COPII vesicles
. It regulates the assembly and disassembly of COPII coats.
GDP-bound Sar1 interacts with the membrane-bound exchange factor Sec12 and exchanges its bound GDP for GTP. The hydrophobic N-terminus of Sar1-GTP then locates it to the membrane, where it serves as the binding site for the Sec23/Sec24 protein coat complex. After the vesicle coat is completely assembled and the vesicle is released from the donor membrane, the Sec23 subunit promotes Sar1 GTPase activity, which triggers the disassembly of the COPII coat.
GTPase
GTPases are a large family of hydrolase enzymes that can bind and hydrolyze guanosine triphosphate . The GTP binding and hydrolysis takes place in the highly conserved G domain common to all GTPases.-Functions:...
found in COPII vesicles
COPII
COPII is a type of vesicle coat protein that transports proteins from the rough endoplasmic reticulum to the Golgi apparatus. This is termed anterograde transport. The name "COPII" refers to the specific coat protein complex that initiates the budding process...
. It regulates the assembly and disassembly of COPII coats.
GDP-bound Sar1 interacts with the membrane-bound exchange factor Sec12 and exchanges its bound GDP for GTP. The hydrophobic N-terminus of Sar1-GTP then locates it to the membrane, where it serves as the binding site for the Sec23/Sec24 protein coat complex. After the vesicle coat is completely assembled and the vesicle is released from the donor membrane, the Sec23 subunit promotes Sar1 GTPase activity, which triggers the disassembly of the COPII coat.