NALOXONE-SENSITIVE, HALOPERIDOL-SENSITIVE [H-3] (-10047-BINDING PROTEIN PARTIALLY PURIFIED FROM RAT-LIVER AND RAT-BRAIN MEMBRANES - AN OPIOID()SKF)SIGMA RECEPTOR/
Li. Tsao et Tp. Su, NALOXONE-SENSITIVE, HALOPERIDOL-SENSITIVE [H-3] (-10047-BINDING PROTEIN PARTIALLY PURIFIED FROM RAT-LIVER AND RAT-BRAIN MEMBRANES - AN OPIOID()SKF)SIGMA RECEPTOR/, Synapse, 25(2), 1997, pp. 117-124
A naloxone-sensitive, haloperidol-sensitive, [H-3](+)SKF-10047-binding
protein was partially purified from rat liver and rat brain membranes
in an affinity chromatography originally designed to purify sigma rec
eptors. Detergent-solubilized extracts from membranes were adsorbed to
Sephadex G-25 resin containing an affinity ligand for sigma receptors
: l)-N-(6-aminohexyl)-(2-[1-pyrrolidinyl])ethylamine (DAPE). After elu
ting the resin with haloperidol, a protein that bound [H-3](+)SKF-1004
7 was detected in the eluates. However, the protein was not the sigma
receptor [H-3](+)SKF-10047 binding to the protein was inhibited by the
following compounds in the order of decreasing potency: (+)pentazocin
e > (-) pentazocine > (+/-)cyclazocine > (-)morphine > (-)naloxone > h
aloperidol > (+)SKF-10047 > DADLE > (-)SKF-10047. Further, the prototy
pic sigma receptor ligands, such as 1,3-di-o-tolylguanidine (DTG), (+)
3-PPP, and progesterone, bound poorly to the protein. Tryptic digestio
n and heat treatment of the affinity-purified protein abolished radiol
igand binding. Sodium dodecyl sulfate/polyacrylamide gel electrophores
is (SDS/PAGE) of the partially-purified protein from the liver reveale
d a major diffuse band with a molecular mass of 31 kDa, a polypeptide
of 65 kDa, and another polypeptide of > 97 kDa. This study demonstrate
s the existence of a novel protein in the rat liver and rat brain whic
h binds opioids, benzomorphans, and haloperidol with namomolar affinit
y. The protein resembles the opioid/sigma receptor originally proposed
by Martin et al. [(1976): J. Pharmacol. Exp. Ther., 197:5 17-532.]. A
high degree of purification of this protein has been achieved in the
present study. (C) 1997 Wiley-Liss, Inc.