Analytical purification of the slow, high affinity NGF receptor: identification of a novel 135 kd polypeptide

Although nerve growth factor (NGF) action is mediated by the slow, high affinity NGF receptor, little is known regarding its molecular composition or mode of action. We have used reversible chemical cross-linkers and affinity chromatography strategies to purify the slow NGF receptor covalently cross-linked to its NGF ligand. Subsequent uncoupling of the cross-links reveals that the receptor-ligand complex is composed of only a novel 135 kd polypeptide interacting with NGF. The previously characterized 85 kd fast, low affinity NGF receptor is not a component of the cross-linked slow receptor-ligand complex. This newly identified 135 kd polypeptide is either the entire slow NGF receptor, or it might be one component of a larger, multisubunit slow NGF holo-receptor.