GTP-binding protein

Function

GTP-binding proteins or G proteins are transmitting signals outside the cell which cause changes within the cell. They act as molecular switches which are on when binding GTP and off when binding GDP. GTP-binding proteins belong to two families: heterotrimeric G proteins^[1] and small GTPases^[2]. The structure of small GTPase is homologous to that of the α subunit of heterotrimeric G protein. See details on GTP-binding protein LepA in LepA.

(human β-2 adrenergic receptor in blue ) in a complex with a heterotrimeric G protein (3 subunits:reddish to orange-brown) and hormone (gold) (3sn6), resolution 3.2Å. The boundaries of the membrane in which the GPCR sits are represented in light green.

Structural highlights

E. coli small GTPase ERA binds GDP in a cavity formed by 3 highly conserved regions^[3].