Lateral mobility of proteins and lipids in the red cell membrane and the activation of adenylate cyclase by beta-adrenergic receptors.

Models of beta-adrenergic signal transduction in red blood cell membranes frequently assume that at least one of the membrane-bound components is laterally mobile and distributes the hormonal signal in the membrane plane. However, direct measurements reveal that protein lateral mobility in the red cell membrane is severely restricted. Furthermore, the spectrin-actin compartmentalizes the cytoplasmic face of the red cell membrane into a regular array of small elementary areas. These considerations support models in which the beta-adrenergic signal is spread in the membrane plane by a molecule which has binding sites on the membrane but diffuses in the aqueous compartment.