Immunoglobulin heavy variable 4-59 (Ig heavy chain V-II region NEWM)
1_MKHLW 6_ FFLLL 11_ VAAPR 16_ WVLSQ 21_ VQLQE 26_ SGPGL 31_ VKPSE 36_ TLSLT 41_ CTVSG 46_ GSISS 51_ YYWSW 56_ IRQPP 61_ GKGLE 66_ WIGYI 71_ YYSGS 76_ TNYNP 81_ SLKSR 86_ VTISV 91_ DTSKN 96_ QFSLK 101_ LSSVT 106_ AADTA 111_VYYCA
1: V region of the variable domain of immunoglobulin heavy chains that participates in the antigen recognition (PubMed:24600447). Immunoglobulins, also known as antibodies, are membrane-bound or secreted glycoproteins produced by B lymphocytes. In the recognition phase of humoral immunity, the membrane-bound immunoglobulins serve as receptors which, upon binding of a specific antigen, trigger the clonal expansion and differentiation of B lymphocytes into immunoglobulins-secreting plasma cells. Secreted immunoglobulins mediate the effector phase of humoral immunity, which results in the elimination of bound antigens (PubMed:20176268, PubMed:22158414). The antigen binding site is formed by the variable domain of one heavy chain, together with that of its associated light chain. Thus, each immunoglobulin has two antigen binding sites with remarkable affinity for a particular antigen. The variable domains are assembled by a process called V-(D)-J rearrangement and can then be subjected to somatic hypermutations which, after exposure to antigen and selection, allow affinity maturation for a particular antigen (PubMed:17576170, PubMed:20176268)