Trypsin pretreatment dissociates the effect of GTP and Na/sup +/ on ligand binding to human platelet. cap alpha. /sub 2/-adrenoreceptors

Conference · Sat Mar 01 00:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5451228

Periyasamy, S M; Somani, P

The authors recently showed that maximal concentration of trypsin (TR) inactivated only 70-80% of specific (/sup 3/H)yohimbine (/sup 3/H-Y) binding to human platelet ..cap alpha../sub 2/-adrenoreceptors (..cap alpha../sub 2/-AR). The effect of TR on the interaction between the agonist, epinephrine, and GTP or Na/sup +/ on /sup 3/H-Y binding to ..cap alpha../sub 2/-AR of human platelets was investigated in the present study. Partially purified ..cap alpha../sub 2/-AR protein was pretreated with 500 ..mu..g TR for 3 min at 35/sup 0/C, the proteolytic action was terminated by specific TR-inhibitor, and the membranes were washed twice prior to specific ligand binding studies. Under these conditions, TR produced a 40-50% reduction of specific /sup 3/H-Y binding. Further characterization of the specific ligand binding by Scatchard plots showed that TR did not modify the affinity of the ..cap alpha../sub 2/-AR to the agonist or the antagonist or the antagonists. However, in the TR-pretreated membranes, the ability of GTP to reduce the receptor affinity for epinephrine was lost. The effect of Na/sup +/, on the other hand, remained intact under these conditions. Thus, TR can selectively destroy the GTP-..cap alpha../sub 2/-AR but not Na/sup +/-..cap alpha../sub 2/-AR interaction suggesting that the GTP- and Na/sup +/-binding proteins are distinct.

• Research Organization: Medical College of Ohio, Toledo
• OSTI ID: 5451228
• Report Number(s): CONF-8604222-; TRN: 86-028329
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
SYMPATHOLYTICS
BIOCHEMICAL REACTION KINETICS
SYMPATHOMIMETICS
RECEPTORS
TRYPSIN
BIOLOGICAL EFFECTS
ADRENALINE
AFFINITY
BLOOD PLATELETS
CELL MEMBRANES
GUANOSINE
LIGANDS
SODIUM COMPOUNDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ADRENAL HORMONES
ALKALI METAL COMPOUNDS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARDIOTONICS
CARDIOVASCULAR AGENTS
CELL CONSTITUENTS
DRUGS
ENZYMES
HETEROCYCLIC COMPOUNDS
HORMONES
HYDROLASES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MATERIALS
MEMBRANE PROTEINS
MEMBRANES
NEUROREGULATORS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEPTIDE HYDROLASES
PROTEINS
PURINES
REACTION KINETICS
RIBOSIDES
SERINE PROTEINASES
STEROID HORMONES
550201* - Biochemistry- Tracer Techniques