Immunoglobulin heavy constant delta (Ig delta chain C region) (Ig delta chain C region NIG-65) (Ig delta chain C region WAH)
1_APTKA 6_ PDVFP 11_ IISGC 16_ RHPKD 21_ NSPVV 26_ LACLI 31_ TGYHP 36_ TSVTV 41_ TWYMG 46_ TQSQP 51_ QRTFP 56_ EIQRR 61_ DSYYM 66_ TSSQL 71_ STPLQ 76_ QWRQG 81_ EYKCV 86_ VQHTA 91_ SKSKK 96_ EIFRW 101_ PESPK 106_ AQASS 111_ VPTAQ 116_ PQAEG 121_ SLAKA 126_ TTAPA 131_ TTRNT 136_ GRGGE 141_ EKKKE 146_ KEKEE 151_ QEERE 156_ TKTPE 161_ CPSHT 166_ QPLGV 171_ YLLTP 176_ AVQDL 181_ WLRDK 186_ ATFTC 191_ FVVGS 196_ DLKDA 201_ HLTWE 206_ VAGKV 211_ PTGGV 216_ EEGLL 221_ ERHSN 226_ GSQSQ 231_ HSRLT 236_ LPRSL 241_ WNAGT 246_ SVTCT 251_ LNHPS 256_ LPPQR 261_ LMALR 266_ EPAAQ 271_ APVKL 276_ SLNLL 281_ ASSDP 286_ PEAAS 291_ WLLCE 296_ VSGFS 301_ PPNIL 306_ LMWLE 311_ DQREV 316_ NTSGF 321_ APARP 326_ PPQPR 331_ STTFW 336_ AWSVL 341_ RVPAP 346_ PSPQP 351_ ATYTC 356_ VVSHE 361_ DSRTL 366_ LNASR 371_ SLEVS 376_YVTDH
1: Constant region of immunoglobulin heavy chains. 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). IgD is the major antigen receptor isotype on the surface of most peripheral B-cells, where it is coexpressed with IgM. The membrane-bound IgD (mIgD) induces the phosphorylation of CD79A and CD79B by the Src family of protein tyrosine kinases. Soluble IgD (sIgD) concentration in serum below those of IgG, IgA, and IgM but much higher than that of IgE. IgM and IgD molecules present on B cells have identical V regions and antigen-binding sites. After the antigen binds to the B-cell receptor, the secreted form sIgD is shut off. IgD is a potent inducer of TNF, IL1B, and IL1RN. IgD also induces release of IL6, IL10, and LIF from peripheral blood mononuclear cells. Monocytes seem to be the main producers of cytokines in vitro in the presence of IgD (PubMed:10702483, PubMed:11282392, PubMed:8774350)