Immunoglobulin kappa variable 3D-20
1_METPA 6_ QLLFL 11_ LLLWL 16_ PDTTG 21_ EIVLT 26_ QSPAT 31_ LSLSP 36_ GERAT 41_ LSCGA 46_ SQSVS 51_ SSYLA 56_ WYQQK 61_ PGLAP 66_ RLLIY 71_ DASSR 76_ ATGIP 81_ DRFSG 86_ SGSGT 91_ DFTLT 96_ ISRLE 101_ PEDFA 106_ VYYCQ 111_QYGSS
1: V region of the variable domain of immunoglobulin light 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)