Protein-fragment complementation assay

A protein - fragment complementation assay, briefly PCA is a biochemical method for detecting in vivo protein-protein interactions.


Selection of antibodies

For in vivo selection of antibody, the enzyme is dihydrofolate reductase is used which is divided into two protein fragments which are not functional individually. The gene segment that encodes for a part of the enzyme is fused to the genetic information of an antigen. This gives this enzyme as a protein part of the antigen - day. The other part of the enzyme, now gets a similar manner, an antibody fragment, attached in the form of a library. Now binds a random antibody to the antigen, the two halves of the enzyme are again brought close enough together that they can form an active enzyme. Because it is the dihydrofolate reductase is an enzyme which the bacteria cells need for survival only those cells survive which have a suitable antibody for the antigen. These cells are then propagated in the rule, and the gene segment encoding for the antibody sequenced to examine in more detail to the antibody.


  • Biochemical method