Journal of Neuroscience, Vol 6, 3767-3776, Copyright © 1986 by Society for Neuroscience
Cross-linking of atrial natriuretic peptide to binding sites in rat olfactory bulb membranes
GM Wildey and CC Glembotski
Binding sites for 125I-atrial natriuretic peptide (ANP)2 in rat olfactory
bulb membranes have been studied using pharmacological and biochemical
methods. Various unlabeled ANP-related peptides were tested for the ability
to inhibit the binding of the radioligand in membrane binding assays.
ANP(92-126) and ANP(99-126) were the most potent inhibitors tested, both
exhibiting an IC50 value of 0.40 nM. ANP(103- 126) and ANP(103-123) were 3
and 70 times less potent, respectively. ANP(111-126) was unable to inhibit
the binding of the radioligand at a concentration of 1 microM. Several
peptides unrelated to ANP were unable to inhibit the binding of the
radioligand to rat olfactory bulb membranes. Membranes labeled with
125I-ANP were incubated with cross- linking agents and subjected to
SDS-PAGE followed by autoradiography. A band possessing an apparent
molecular mass of 116 kDa was identified. The labeling of this band was
progressively decreased by increasing concentrations of unlabeled
ANP(99-126) (IC50 = 0.6 nM) and by several other ANP-related peptides at
nanomolar concentrations. For comparison purposes, ANP binding sites in rat
aorta membranes were labeled with 125I-ANP and cross-linked using identical
techniques. Three bands possessing molecular masses of 120, 72, and 62 kDa
were identified. These results indicate that the ANP binding site in rat
olfactory bulb membranes displays pharmacological and biochemical
properties similar to peripheral ANP receptors.