עיגון זנב של חלבונים בממברנה ER

Tail-anchored or TA proteins are a special class of proteins anchored to the ER membrane via a single hydrophobic, transmembrane domain present at their C-terminal.

Their transmembrane domain also acts as an ER signal sequence that helps in the protein recruitment to the ER membrane.

As soon as a TA protein exits the ribosome, it's C terminal domain is recognized by Sgt2, a protein chaperone.

The Sgt2 then forms a pre-targeting complex with Get4 and Get5 to shield the hydrophobic domain of the target protein.

Next, the pre-targeting complex interacts with the ATP-bound Get3 ATPase via Get4.

Get3 protein acts as a chaperone and guides the protein to the Get1/Get2 heterotetrameric complex present on the ER membrane.

A cytosolic domain of the Get2 proteins then captures the Get3-TA protein complex. 

This interaction is further stabilized by the Get1 cytosolic domain.

Hydrolysis of the ATP bound to the Get3 ATPase switches its conformation to an open state aiding the TA protein transfer to the Get1/Get2 complex.

Subsequently, the Get1/Get2 complex inserts the protein into the ER membrane, and the Get3 ATPase is recycled back to the cytosol.

The resultant tail-anchored protein has a fre