Bovine serum albumin （BSA） is used as a blocking agent during Western blotting to reducebackground and non-specific binding. BSA can also be used in other protocols that involveantibodybinding including ELISA, DELFIA, flow cytometry and immunofluorescence/immunocytochemistry.

 牛血清白蛋白（BSA），又称第五组分，是由583个氨基酸残基组成的一条多肽链，肽链中有17对二硫键，分子量约为66kD，等电点4.7。