Complementarity Determining Regions (CDRs)

Question

Complementarity determining regions (CDRs) are part of the variable domains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules bind to their specific antigen. (source: WIKI, with a minor change)

Now does this mean that this CDR is the paratope? As it has the same functionality as paratope, to bind to epitope of the antigen. So is CDR a type of paratope?

(I have not studied biology since last 8 years and now I am going through it because I need it for my research. So if someone can describe it in simple language it would be very helpful)

Answer 1

The paratope is the part of an antibody that binds the epitope on the antigen. The CDRs (heavy chain CDRs shown below) are part of the structure of the variable domain, and contain the hypervariable regions that bind to the epitope.

_{From Wikimedia}

The actual paratope is within the hypervariable regions, which are within the CDRs - the paratope is not necessarily made up of the entire CDR region, and in fact may only be composed of amino acids contained within one or two of the three CDRs on each antibody chain (heavy and light).

If you're in the market for a good introductory immunology text, I highly recommend Janeway's Immunobiology. An earlier version is also available on the NCBI Bookshelf.