Molecular comparison of alpha 1- and alpha 2-adrenergic receptors suggests that these proteins are structurally related "isoreceptors".
AUTOR(ES)
Shreeve, S M
RESUMO
The structures of human platelet alpha 2-adrenergic receptors and rat liver alpha 1-adrenergic receptors were compared by utilizing isoelectric focusing, NaDodSO4/PAGE, and monoclonal antibody crossreactivity. Digitonin-solubilized alpha 1- and alpha 2-adrenergic receptors have an identical isoelectric point of 4.6. Under reducing conditions in NaDodSO4/polyacrylamide gels, the alpha 1-adrenergic receptor has an apparent molecular mass of 85 kDa. Similarly, the alpha 2-adrenergic receptor, which had been affinity-labeled with [3H]phenoxybenzamine and partially purified by isoelectric focusing or photoaffinity-labeled with p-[3,5-3H]azidoclonidine, was also found to have an apparent molecular mass of 85 kDa. One hybridoma, developed from a fusion between SP2/O myeloma cells and splenic lymphocytes from BALB/c mice immunized with human platelet alpha 2-adrenergic receptors, secreted a monoclonal antibody (alpha 2-116p) against the ligand binding site of alpha 2-adrenergic but not alpha 1-adrenergic receptors. In contrast, three monoclonal antibodies raised against the alpha 1-receptor polypeptide backbone but not the ligand binding site were found to specifically immunoprecipitate human platelet alpha 2-adrenergic receptors. These data suggest that the alpha 1- and alpha 2-adrenergic receptors are "isoreceptors," sharing immunogenic and, by implication, structural determinants that most likely evolved as a result of gene duplication.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=391001Documentos Relacionados
- Quantitative autoradiography of beta 1- and beta 2-adrenergic receptors in rat brain.
- Sources of calcium used during alpha 1- and alpha 2-adrenergic contractions in canine saphenous veins.
- Efficacy of beta 1-adrenergic receptors is lower than that of beta 2-adrenergic receptors.
- Characterization and distribution of alpha 2-adrenergic receptors in the human intestinal mucosa.
- Blockade of beta 1- but not of beta 2-adrenergic receptors replicates propranolol's suppression of the cerebral spread of an engram in mice.