Get Complete Information on Hyper Variable Regions or Hot Spots and Immunoglobulins

The amino acids sequence in certain regions of variable domines of both light and heavy chains are highly variable, and they are generally referred as hotspots or hyper variable regions.

The light chain variable domine include three such hyper variable regions, they are between the positions of 24 to 34, 50 to 56 and 89 to 97 amino acid moieties.

In heavy chains there are four such hyper variable regions between 1 to 23, 35 to 49,57 to 88,98 tol07 amino acid moieties. The hyper variable regions brought together to form antigen binding site or the “paratope”.

The chemistry and shape of the paratope is complementary to the epitope of antigen, like the key of a lock. Since epitopes are highly variable in different antigens and even a single antigen processes variable epitopes at the same time, the hyper variability of variable domine in immunoglobulins helps in the production of suitable paratopes to bind with the antigens. As the paratope is very specific for each epitope, the variation in paratope region is responsible for the heterogeneity among the same type of immunoglobulins. For example immunoglobulin G produced in response to different antigens show variation in their variable regions or binding sites only.

The immunoglobulin produced in response to a particular antigen will not bind with the other antigen due to mismatch of their paratope with epitope regions.

Hinge Region:

Hinge region is an extend peptide sequence between CH1 and CH₂ domines of heavy chain.

It is rich in cysteine and proline amino acids, extremely variable in amino acid sequence, and has no resemblance to any other immunoglobulin region. It provides flexibility to the antigen binding part of immunoglobulin. Because of high proline content, hinge region is highly vulnerable to lytic enzymes such as papain and pepsin.

The cystein residues in this region help in establishing the disulphide bond with opposite heavy chain. The number of disulphide bonds depends on the length of hinge region; generally they range from 1-13.

Hinge region is absent in immunoglobulins of mu (p) type and epsilon (e) type. Instead of hinge they have additional constant domine that functions like that of a hinge region.