Addition of a signal peptide sequence to theα1D-adrenoceptor gene increases the density of receptors, as determined by [3H]-prazosin binding in the membranes

1 Both in mammalian tissues and in transfected cells, only low levels of α1D-adrenoceptors are detected in radioligand binding studies. It has been implicated that the comparatively long N-terminal tail of the α1D-adrenoceptor is responsible for the inefficient surface expression of the receptor. 2 In the present study, we created gene constructs for six N-terminally truncated variants of the human α1D-adrenoceptor. These constructs were used to transfect Neuro2A cells. We show that the density of α1D-adrenoceptors, observed by [3H]-prazosin binding, gradually increased with longer truncations of the N-terminus. This seems to indicate that the long N-terminal tail nonspecifically interferes…