recognition site 

https://doi.org/10.1351/goldbook.R05199
  1. A nucleotide sequence to which a protein binds specifically.
  2. An amino acid sequence in an antibody molecule to which the specific antigen binds specifically.
Source:
PAC, 1992, 64, 143. (Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)) on page 164 [Terms] [Paper]