Reserpine binding to chromaffin granules suggests the existence of two conformations of the monoamine transporter

Journal Article · Tue Feb 21 04:00:00 EST 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00430a040· OSTI ID:5719155

Darchen, F; Scherman, D; Henry, J P ^[1]

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1. Institut de Biologie Physico-Chimique, Paris (France)

The binding of ({sup 3}H)reserpine (({sup 3}H)RES) to purified bovine chromaffin granule membranes has been studied at low membrane concentration. Saturation isotherms indicated a dissociation equilibrium constant K{sub D} of 30 pM and a density of binding sites of 8 pmol/mg of protein at 30 {degree}C. The association rate constant was 4.0 x 10{sup 5} M{sup {minus}1} s{sup {minus}1}, and the calculated dissociation rate constant was 1.2 x 10{sup {minus}5} s{sup {minus}1}, corresponding to a half-lifetime of about 16 h. Although this dissociation was too low to be measured directly, ({sup 3}H)RES binding was indeed reversible since it was lost after addition of the detergent Triton X-100. Dihydrotetrabenazine (TBZOH) inhibited ({sup 3}H)RES binding in a time-dependent manner. On the contrary, ({sup 3}H)RES binding inhibition by the substrate noradrenaline was time independent. It is proposed that the transporter exists in two different conformations which bind exclusively either tetrabenazine (TBZ) or RES and which are in equilibrium. The effects of detergents were consistent with this two-conformational model. It is proposed that the TBZ-binding conformation is obtained by solubilization with cholate and that RES stabilizes the RES-binding conformation, allowing its solubilization by this detergent.

• OSTI ID: 5719155
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:4; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALOIDS
ANIMALS
ANTIHYPERTENSIVE AGENTS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
AZOLES
BIOCHEMICAL REACTION KINETICS
CARDIOVASCULAR AGENTS
CATTLE
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
CONFORMATIONAL CHANGES
CROSS-LINKING
DOMESTIC ANIMALS
DOSE-RESPONSE RELATIONSHIPS
DRUGS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INDOLES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
POLYMERIZATION
PROTEINS
PYRROLES
REACTION KINETICS
RECEPTORS
RESERPINE
RUMINANTS
SYMPATHOLYTICS
TIME DEPENDENCE
TRITIUM COMPOUNDS
VERTEBRATES