External location of sites on pig erythrocyte membranes that bind nitrobenzylthioinosine

Journal Article · Tue Mar 01 04:00:00 EST 1988 · Mol. Pharmacol.; (United States)

OSTI ID:7066581

Agbanyo, F R; Cass, C E; Paterson, A R

Nucleoside transport in erythrocytes of various species is inhibited by the binding of nitrobenzylthioinosine (NBMPR) to high affinity sites associated with nucleoside transport elements of the plasma membrane. The present study examined binding of (/sup 3/H)NBMPR to unsealed ghosts and to sealed right-side-out vesicles (ROVs) and inside-out vesicles (IOVs) prepared from pig erythrocytes. Kd values for NBMPR dissociation from the ligand-site complex in unsealed ghosts, ROVs and IOVs were similar (1.6-2.4 nM), and Bmax values (mean +/- SD) were, respectively, 22.2 +/- 5.5, 25.8 +/- 6.4, and 37.3 +/- 4.0 molecules/fg of protein, reflecting differences in the protein content of the membrane preparations. When temperatures were decreased from 22 degrees to 4 degrees, NBMPR binding to erythrocyte membrane preparations was reduced in IOVs relative to that in unsealed ghosts and ROVs. At 22 degrees, the association of NBMPR molecules with IOVs was slower than with ROVs and unsealed ghosts, differences that were virtually eliminated by permeabilization of the membrane preparations with saponin. Thus, the binding sites were more accessible to external NBMPR in sealed ROVs and unsealed ghosts than in sealed IOVs, indicating that the NBMPR sites are located on the extracellular aspect of the membrane.

• Research Organization: Univ. of Alberta, Edmonton (Canada)
• OSTI ID: 7066581
• Journal Information: Mol. Pharmacol.; (United States), Journal Name: Mol. Pharmacol.; (United States) Vol. 33:3; ISSN MOPMA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
AROMATICS
AZAARENES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOHYDRATES
CELL CONSTITUENTS
CELL MEMBRANES
DOMESTIC ANIMALS
ERYTHROCYTES
GLYCOSIDES
HETEROCYCLIC COMPOUNDS
IN VITRO
INOSINE
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MEMBRANES
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PERMEABILITY
PROTEINS
PURINES
REACTION KINETICS
RECEPTORS
RIBOSIDES
SAPONINS
SWINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES