CHEMOLABELING OF FROZEN CEREBRAL TISSUE PROTEINS AND IMMUNOPURIFIED PRODUCTS WITH BIOTIN AND DIGOXIGENIN - PHYSICOCHEMICAL CHARACTERISTICS OF BIOTINYLATED AND DIGOXIGENINATED PRODUCTS

Biotinylation and digoxigenination have been compared for labeling pro teins from a total frozen tissue extract and from products of immunopu rification with anti-RAR beta (retinoic acid receptor beta). The detec tion of biotinylated and digoxigeninated proteins was found to be easi er and more sensitive than detection of silver-stained proteins after two-dimensional electrophoresis. Although biotinylated or digoxigenina ted proteins can be detected with avidin conjugates or anti-digoxigeni n antibodies, they can also be detected with specific antibodies such as anti-RAR beta antibodies. Previously, coimmunoprecipitates could be visualized only by radioactive amino acid incorporation in cell cultu re, whereas biotinylation and digoxigenination enable the study of spe cific protein expression in frozen tissues by immunoprecipitation and the visualization of coimmunoprecipitates. Chemolabeling presents the two major advantages of limiting the use of radioisotopes and allowing the use of frozen tissues in all types of protein expression studies. (C) 1994 Academic Press, Inc.