Membrane receptor systems on the surface of cells in many instances are indicators or determinants not only of the developmental state of the cell, but also of pathological states. Cell populations are presented with a vast array of small molecules that influence the cell through surface membrane structures. At present, the spatial and interactive relationships between different kinds of receptors is unclear. The purpose of this project is to study these relationships using two different cell populations (skeletal muscle and sympathetic ganglia). Several different types of receptors in these two tissues will be studied. The control and integration of these receptor systems will be studied in vitro. The results of these experiments should increase the understanding not only of the individual receptor systems but also of the mechanisms which mediate the integration of multiple receptor inputs. In addition, the multiple stage affinity system described should add a new dimension to the purification of unique membrane domains.