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Sequestration of 125 I‐Labeled p Nerve Growth Factor by Embryonic Sensory Neurons
Author(s) -
Olender Edward J.,
Wagner Barbara J.,
Stach Robert W.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb00474.x
Subject(s) - internalization , receptor , nerve growth factor , dissociation constant , chemistry , dissociation (chemistry) , biophysics , sensory system , biology , neuroscience , biochemistry
Nerve growth factor (NGF) binds to two specific receptors on sensory nerve cells. These two receptors are characterized by different equilibrium dissociation constants. The higher affinity (type I) receptors have an equilibrium dissociation constant of 3.3 × 10 ‐11 M. The lower affinity (type II) receptors have an equilibrium dissociation constant of 1.7 × 10 ‐9 M. These two receptors are not a result of negative cooperatively, but apparently are different receptors. At 22°C the rate of association is 1 × 10 7 M ‐1 S ‐1 and the rates of dissociation are 6.5 × 10 ‐4 s ‐1 (type I) and 3.2 × 10 ‐2 s ‐1 ’(type II). After binding, a time‐dependent process occurs that makes the NGF inaccessible to the external milieu (sequestered). The sequestration process is energy‐dependent, but apparently temperature‐independent. The data suggest that only the type I receptors are involved in the sequestration process. This process is similar to that observed on sympathetic neurons and may be the first step in the internalization of NGF by responsive cells.