14C-labeled proteins as markers for gradient analysis of steroid-hormone receptors.
Two useful [14C]marker proteins--[14C]human serum albumin (4.6S) and [14C]glucose oxidase (7.9S)--can be simply prepared. Both may be used as molecular-mass standards in polyacrylamide gel electrophoresis as sucrose density-gradient centrifugation. The utility of these markers for estrogen receptor studies was investigated under a variety of conditions, to ensure that they do not interfere with current assay procedures. Their use as internal markers allows more samples to be analyzed per rotor, a significant factor because each centrifugation run requires 16 h and two bucket spaces for each sample assayed; improves accuracy and overall quality control by eliminating any problems resulting from variations among individual gradients; and facilitates evaluation of changes in gradient profiles, which may provide clinically and biochemically relevant information concerning the microheterogeneity of estrogen receptors.
D001943:Breast Neoplasms / Q000032:analysis; D002250:Carbon Radioisotopes; D003600:Cytosol / Q000032:analysis; D005260:Female; D005949:Glucose Oxidase; D006801:Humans; D011865:Radioisotope Dilution Technique; D011987:Receptors, Steroid / Q000032:analysis*; D012709:Serum Albumin; D014316:Tritium
D002250:Carbon Radioisotopes; D011987:Receptors, Steroid; D012709:Serum Albumin; D014316:Tritium; D005949:Glucose Oxidase