CDRH1

CDRH1 stands for complementarity-determining region 1 of the heavy chain variable region in antibodies. It is one of the six hypervariable loops that together form the antigen-binding site of an immunoglobulin heavy chain.

It is located between framework regions FR1 and FR2 in the heavy chain variable domain. The sequence and length of CDRH1 vary among antibodies, contributing to the diversity of antigen recognition. CDRH1, along with CDRH2 and CDRH3, shapes the paratope and often participates directly in contact with antigen.

Genetically, CDRH1 arises from the IGHV gene segment used in assembling the heavy chain variable domain during V(D)J recombination, and it can be further diversified by somatic hypermutation during affinity maturation. This variability underpins the immune system’s ability to recognize a wide range of epitopes.

In research and therapeutic contexts, CDRH1 is a central element in antibody design, humanization, and structure-based modeling. Comparative analyses of CDRH1 sequences across antibodies and species aid in understanding binding properties and informing grafting strategies that preserve antigen specificity while reducing immunogenicity.

CDRH1 is defined in standard antibody numbering schemes such as Kabat, Chothia, and IMGT, which delineate its boundaries relative to surrounding framework regions.