Journal of Neuroscience, Vol 8, 3067-3073, Copyright © 1988 by Society for Neuroscience
Characterization of solubilized atrial natriuretic peptide receptors from rat olfactory bulb and A10 cultured smooth muscle cells
TR Gibson, AD Zyskind and CC Glembotski
Molecular Biology Institute, San Diego State University, California 92182.
Atrial natriuretic peptide (ANP) receptors from A10 cultured vascular
smooth muscle cells (VSMC) and rat olfactory bulbs have been solubilized
and then pharmacologically and biochemically compared. The dissociation
constant for 125I-ANP(99-126) was 12.7 pM for the VSMC- derived receptor
and 164 pM for the olfactory receptor. Competition binding between
125I-ANP(99-126) and several unlabeled ANP analogs with the soluble
olfactory receptor, demonstrated a rank order potency of ANP(99-126) =
ANP(103-126) much greater than ANP(103-123). However, the rank order
potency of the soluble VSMC ANP receptor was ANP(99-126) = ANP(103-126) =
ANP(103-123). Therefore, the olfactory ANP receptor appears to require the
complete COOH-terminal sequence of ANP as compared with the VSMC ANP
receptor. When the 2 soluble receptor preparations were applied to a
GTP-agarose column, a portion of the olfactory ANP receptor was retained on
the column and could be eluted with 5 mM GTP, while the VSMC ANP receptor
did not adsorb to the column. Since the olfactory bulb ANP receptor has
been shown to contain a binding component of 116 kDa, while the VSMC ANP
receptor binding component is 66 kDa, these receptors appear to be similar
to the 2 receptor classes described recently in which the 120 kDa receptor
that binds GTP is postulated to be coupled to guanylate cyclase, while the
60 kDa receptor does not bind GTP, is not coupled to guanylate cyclase, and
may possess a hormone clearance function. Taken together, these data
indicate that cyclic GMP appears to be a second messenger for ANP in the
brain.