title: The beta 1-adrenergic receptor of the turkey erythrocyte. Molecular heterogeneity revealed by purification and photoaffinity labeling.
abstract: The beta 1-adrenergic receptor of turkey erythrocytes has been purified by a combination of affinity and high performance steric exclusion chromatography. These procedures provide preparations with specific activities of greater than 15,000 pmol/mg of protein with an overall recovery of approximately 30% of the receptor activity solubilized from membrane preparations. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of radioiodinated purified receptor reveals two bands of labeled protein with apparent Mr = 40,000 +/- 2,000 and 45,000 +/- 3,000  in a 3-4:1 ratio. These same two peptides can also be labeled specifically and in approximately the same ration in both membranes and purified preparations using the photoaffinity probe 125I-labeled p-azidobenzylcarazolol. When the two purified polypeptides are completely separated by high performance liquid chromatography and subjected to detailed ligand binding studies, identical beta 1-adrenergic specificities are found for the two receptor forms. Preliminary characterization of these two proteins by partial protease digestion suggests a large degree of similarity between them, albeit with some significant differences. These results demonstrate that both purification and photoaffinity labeling identify two polypeptides in turkey erythrocyte membranes as containing a beta 1-adrenergic receptor binding site. The functional and structural relationships of these two forms of the receptor remain to be elucidated.
mesh_terms: D000345:Affinity Labels / Q000378:metabolism; D000818:Animals; D002918:Chymotrypsin / Q000378:metabolism; D004912:Erythrocytes / Q000032:analysis*; D007525:Isoelectric Focusing; D008970:Molecular Weight; D010206:Papain / Q000378:metabolism; D010777:Photochemistry; D011941:Receptors, Adrenergic / Q000302:isolation & purification*; D011943:Receptors, Adrenergic, beta / Q000302:isolation & purification*; D014357:Trypsin / Q000378:metabolism; D014422:Turkeys
chemical_list: D000345:Affinity Labels; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D002918:Chymotrypsin; D014357:Trypsin; D010206:Papain