Studying the copy number of ribosomal protein L7/L12. 
Studying the copy number of ribosomal protein L7/L12 was performed using monoclonal antibody 3G9 to the linear epitope on the C-terminal domain of this protein from Escherichia coli.  Immunohistochemical study showed that Agrobacterium tumefaciens ribosomes include 6 copies of protein L7/L12.  Our results suggest that the copy number of this protein has an evolutionary role.