Topological analysis of the human beta2 adrenergic receptor expressed in Escherichia coli

We have investigated the topology of the human jJ2-adrenerglc receptor expressed inEscherichia col, using the genetic method described by B wth and coworkers. We found that fusin with alkali phhatse beyond a certain point on the human 2-adrenerglc receptor sequence were assembled into the bacterial membrane with the same topology as the human P2-adrenergic receptor in the mammalan membrane. The pattern that might have been expected on the basis of the topology of the human Az-adrenerglc receptor in a membranes was not reflected in the levels of alkaline phosphatase activity of the fusions occurring between the N-terminal region and postions close to the second ex l domain. Our data suggest that the correct positioning of the N terminus of the receptor depends on the presence of its C-terminal portions.