Dimerization of β-adrenergic receptor is responsible for the constitutive activity subjected to inverse agonism.

Dimerization of beta 2-adrenergic receptor (β-AR) has been observed across various physiologies. However, the function of dimeric β-AR is still elusive. Here, we revealed that dimerization of β-AR is responsible for the constitutive activity of β-AR generating inverse agonism. Using a co-immunoimmobilization assay, we found that transient β-AR dimers exist in a resting state, and the dimer was disrupted by the inverse agonists. A Gα preferentially interacts with dimeric β-AR, but not monomeric β-AR, in a resting state, resulting in the production of a resting cAMP level. The formation of β-AR dimers requires cholesterol on the plasma membrane. The cholesterol did not interfere with the agonist-induced activation of monomeric β-AR, unlike the inverse agonists, implying that the cholesterol is a specific factor regulating the dimerization of β-AR. Our model not only shows the function of dimeric β-AR but also provides a molecular insight into the mechanism of the inverse agonism of β-AR.