PMC

The α_1B-adrenoceptor traffics to the cell surface as a dimer/oligomer. A form of the α_1B-adrenoceptor containing mutations in transmembrane domains (TM) I and IV (α_1BTMITMIV, blue) () is retained in the endoplasmic reticulum (ER) when expressed in HEK293 (human embryonic kidney) cells and study employing bimolecular fluorescence complementation indicate that it exists as a dimer/oligomer (). Sustained treatment of such cells with the α₁-adrenoceptor antagonist prazosin results in maturation of the receptor and its movement to the plasma membrane (PM). A form of the α_1B-adrenoceptor that is wild-type except that it contains an Asp¹²⁵Ala mutation that eliminates its ability to bind prazosin (α_1BD¹²⁵A, yellow) is delivered successfully to the PM when expressed. When α_1BD¹²⁵A is co-expressed with α_1BTMITMIV, α_1BD¹²⁵A becomes ER-retained because α_1BTMITMIV interacts with α_1BD¹²⁵A and functions as a ‘dominant negative’. Treatment of these cells with prazosin results in movement of both α_1BTMITMIV and α_1BD¹²⁵A to the cell surface. As α_1BD¹²⁵A cannot bind prazosin, these observations indicate that the two forms of the α_1B-adrenoceptor move to the PM as a dimer/oligomer (see for further details).