title: Covalent labeling of the beta-adrenergic ligand-binding site with para-(bromoacetamidyl)benzylcarazolol. A highly potent beta-adrenergic affinity label.
abstract: para-(Bromoacetamidyl)benzylcarazolol (pBABC) was synthesized and found to be an extremely potent affinity label for beta-adrenergic receptors. Its interaction with mammalian (rabbit and hamster lung) and nonmammalian (turkey and frog erythrocyte) beta-adrenergic receptors was similar, displaying EC50 values of 400-900 pM for inhibiting 125I-cyanopindolol binding to these receptors. pBABC reduced the number of beta-adrenergic receptors in frog erythrocyte membranes, without any change in the affinity of the remaining sites for [125I]iodocyanopindolol. pBABC has been radioiodinated. As assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, this affinity probe specifically labeled the beta-adrenergic peptide of a purified preparation of hamster lung, with high efficiency (approximately 40%) and with a pharmacological specificity characteristic of an interaction at the beta 2-adrenergic receptor ligand-binding site. Comparison of the proteolyzed products derived from purified receptor labeled with [125I]pBABC and with the photoaffinity agent [125I]p-azidobenzylcarazolol suggested that covalent labeling of the beta-adrenergic receptor by these probes occurs at similar domains of the beta-adrenergic receptor. Because of the much higher level of incorporation of this affinity probe as opposed to photosensitive probes, pBABC should prove to be a useful tool for structural studies of purified beta-adrenergic receptors.
authors.forename: K E
authors.initials: KE
authors.lastname: Dickinson
authors.forename: S L
authors.initials: SL
authors.lastname: Heald
authors.forename: P W
authors.initials: PW
authors.lastname: Jeffs
authors.forename: R J
authors.initials: RJ
authors.lastname: Lefkowitz
authors.forename: M G
authors.initials: MG
authors.lastname: Caron
mesh_terms: D000345:Affinity Labels / Q000378:metabolism*; D000818:Animals; D006224:Cricetinae; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D020120:Iodocyanopindolol; D008024:Ligands; D008168:Lung / Q000378:metabolism; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011412:Propanolamines / Q000378:metabolism*; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000345:Affinity Labels; D007457:Iodine Radioisotopes; D008024:Ligands; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; C045262:4-(bromoacetamido)benzylcarazolol; D010869:Pindolol