Dispersed sensory ganglion cells cleave an active entity from nerve growth factor coupled to Sepharose

Dispersed sensory ganglion cells from the embryonic chick, but not cells from other tissues, liberate biologically active material from nerve growth factor coupled to Sepharose beads. Experiments with such insolubilized material cannot then be taken as evidence for the existence of an external membrane receptor for the factor and may indicate that responsive cells have the ability to cleave an active fragment from the polypeptide.