Identification of the Subunit Structure of Rat Pineal Adrenergic Receptors by Photoaffinity Labeling

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Abstract: The adrenergic receptors of rat pineal gland were investigated using radiolabeled ligand binding and photoaffinity labeling techniques. 125I‐2‐[β‐(4‐hydroxyphenyl)ethylaminomethyl]tetralone (125I‐HEAT) and 125I‐cyanopindolol (125I‐CYP) labeled specific sites on rat pineal gland membranes with equilibrium dissociation constants (KD) of 48 (±5) pM and 30 (±5) pM, respectively. Binding site maxima were 481 (±63) and 1,020 (±85) fmol/mg protein. The sites labeled by 125I‐HEAT had the pharmacological characteristics of α1‐adrenergic receptors. 125I‐CYP‐labeled β‐adrenergic receptors were characterized as a homogeneous population of β1‐adrenergic receptors. The α1‐ and β1‐adrenergic receptors were covalently labeled with the specific photoaffinity probes 4‐amino‐6,7‐dimethoxy‐2‐{4‐[5‐(4‐azido‐3‐[125I]iodo‐phenyl) pentanoyl]‐1‐piperazinyl}quinazoline (125I‐APDQ) and 125I‐p‐azidobenzylcarazolol (125I‐pABC). 125I‐APDQ labeled an α1‐adrenergic receptor peptide of Mr= 74,000 (±4,000), which was similar to peptides labeled in rat cerebral cortex, liver, and spleen. 125I‐pABC labeled a single β1‐adrenergic receptor peptide with a Mr= 42,000 (±1,500), which differed from the 60–65,000 peptide commonly seen in mammalian tissues. Possible reasons for these differences are discussed.


Externa organisationer
  • Howard Hughes Medical Institute
  • Duke University Medical Center

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Cell- och molekylärbiologi


Sidor (från-till)1153-1160
TidskriftJournal of Neurochemistry
Utgåva nummer4
StatusPublished - 1986 jan 1
Peer review utfördJa
Externt publiceradJa