A rapid immunological spot test for the identification of proteins in covalently linked protein-nucleic acid complexes.

A method is described for the rapid immunological identification of proteins in studies of multicomponent systems. In this case the system is the E. coli ribosome, and the ribosomal proteins to be identified are covalently attached to fragments of labelled ribosomal RNA as a result of chemical cross-linking procedures. Antisera raised against the individual ribosomal proteins are spotted onto a nitrocellulose sheet, and an aliquot of the covalent complex under test is added to each antibody spot. After suitable washing procedures, a positive reaction with one or other of the antisera is visualized by autoradiography of the labelled RNA moiety attached to the antibody via the ribosomal protein. Amounts of protein as low as 10 pg can readily be detected.