“…Quantitative applications of the mobile receptor model are infrequent, but it has been reported to describe the binding of agonists to β-adrenergic receptors (De Lean et al , 1980), D 2 -dopaminergic receptors (Wreggett and De Lean, 1984), A 1 adenosine receptors (Leung et al , 1990), α 2 -adrenergic receptors (Neubig et al , 1988), and M 2 -muscarinic receptors (Ehlert, 1985, 1987; Ehlert and Rathbun, 1990; Minton and Sokolovsky, 1990). Success has been mixed, as illustrated by the common implication that guanyl nucleotides such as GMP-PNP cause an irreversible loss of G proteins from the system. Owing to this and other anomalies, the model has not provided a mechanistically consistent description of the binding patterns and the changes effected by guanyl nucleotides (Wong et al , 1986; Lee et al , 1986).…”