Golgi voltage gates

Golgi Voltage Gates (GVGs) are transmembrane proteins found on the surface of the Golgi apparatus, that allow proteins travelling from the Endoplasmic reticulum in vesicles to enter to the core of the cisternae. It was previously thought that vesicles would fuse with the Cis Golgi Network, but a recent paper published by a team of post-graduates at Imperial College London showed that the presence of these GVGs was vital for the transport of proteins from the Endoplasmic reticulum.
Mechanism
The mechanism for the attachment of a vesicle to a Golgi Voltage Gate is known as the GVG-Vesicle Co-joining Mechanism. Vesicles from the Endoplasmic reticulum have, embedded in their plasma membrane, a special transmembrane protein complex, known as the Ubiquitin-Proton Ionotropic Complex (UPIC). When this is phosphorylated, the GVG attaches itself to any protruding polyhistadine tag within the polypeptide, binding the vesicle to the Cis Golgi Network. Via the action protein kinase B456, this subsequently allows the UPIC to undergo a conformational change, stimulating the opening of a proton channel in its core. A pre-existing electrochemical gradient then enables protons to flow through. The result of these processes means there is a mounting potential difference between the cytosol and the Cis Golgi Network. When this surpasses the threshold voltage (around 140 mV), the GVGs open, making the contents of the vesicle move into the Golgi. Current research is focused on determining the precise atomic structure of UPIC, and results from previous similar experiments are being used as reference points.

Main Menu

See Also

Main Menu