Open AccessProstaglandin‐E 1 ‐binding sites in rabbit erythrocyte membranes
Author(s) -
DUTTAROY Asim K.,
HOQUE Lutful,
PATERSON Brian J.
Publication year - 1993
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1993.tb17867.x
Subject(s) - membrane , dissociation constant , binding site , adenylate kinase , chemistry , binding constant , prostaglandin e1 , cyclase , biophysics , incubation , biochemistry , biology , receptor , endocrinology
Prostaglandin E 1 (PGE 1 ) binding sites have been identified on rabbit erythrocyte membranes. The binding of PGE 1 to the membranes was found to be highly specific, reversible, and saturable. The high‐affinity binding sites had a dissociation constant ( K d,1 ) of 5.6 ± 1.2 nM with a binding capacity of 210 ± 51 fmol/mg protein, whereas the low‐affinity binding sites had a dissociation constant ( K d,2 ) of 22 ± 6.4 μM, and a binding capacity of 321 ± 78 pmol/mg protein. Incubation with PGE 1 did not activate adenylate cyclase in the membranes. Preincubation of rabbit erythrocyte membranes with physiological amounts of insulin (1.5 nM) resulted in an increase of PGE 1 binding to the membranes from 241 ± 65 to 429 ± 85 fmol/mg protein. The insulin‐induced increase in PGE 1 binding was due to an increase in binding sites (both high‐affinity and low‐affinity binding sites) rather than to an increase in the affinity of the binding sites. Treatment of erythrocyte membranes with PGE 1 at concentrations (4.0–7.5 nM) which were within the K d,1 value of the high‐affinity binding sites, resulted in a significant reduction in membrane fluorescence anisotropy (0.27 ± 0.005–0.21 ± 0.003). Use of higher concentrations (>15 nM) of PGE 1 reversed the effect of its lower concentration on the membrane anisotropy.