Immunoglobulin heavy constant gamma 1

免疫球蛋白重常数 γ 1

Homo sapiensTaxon: 9606

3D-structureAdaptive immunityAlternative splicingCell membraneChromosomal rearrangementDirect protein sequencingDisulfide bondGlycoproteinImmunityImmunoglobulinImmunoglobulin domainMembrane+5

Sequence Length

399

amino acids

Molecular Weight

43.9 kDa

theoretical

Experimental Structures

PDB entries

Related Diseases

recorded

Function

Constant region of immunoglobulin (Ig) heavy chains. Igs are membrane-bound or secreted glycoproteins produced by B lymphocytes. In the recognition phase of humoral immunity, the membrane-bound Igs serve as receptors, which upon binding to a specific antigen trigger the clonal expansion and differentiation of B lymphocytes into Ig-secreting plasma cells. Secreted Igs known as antibodies mediate the effector phase of humoral immunity by blocking the interaction of infectious antigens with cellular receptors (via the antigen-binding region) and eliciting effector mechanisms that lead to pathogen neutralization (via the constant region) (PubMed:17576170, PubMed:20176268, PubMed:22158414). The antigen-binding region is formed by the variable domain of one heavy chain paired with the variable domain of its associated light chain. Each Ig molecule has two antigen-binding sites with remarkable affinity for a particular antigen due to V-(D)-J rearrangement, somatic hypermutations and affinity maturation of the variable domains upon antigen exposure (PubMed:17576170, PubMed:20176268, PubMed:22158414). The constant region defines the Ig isotype that perform distinct sets of effector functions. B cells diversify and rearrange their Ig constant regions through class-switch recombination, a process by which the constant region is switched from one Ig isotype to another, namely from IgM and IgD to IgG, IgA and IgE (PubMed:17576170, PubMed:20176268, PubMed:22158414). The constant region of Ig gamma-1 (IgG1) isotype interacts (via the fragment crystallizable, Fc) with receptors on innate immune cells and the complement system to mediate humoral effector functions, including antibody-dependent cellular cytotoxicity or phagocytosis, complement-dependent cytotoxicity and inflammatory responses

免疫球蛋白 (Ig) 重链恒定区。 Igs 是 B 淋巴细胞产生的膜结合或分泌糖蛋白。在体液免疫的识别阶段，膜结合的 Ig 作为受体，与特定抗原结合后触发 B 淋巴细胞克隆扩增并分化为分泌 Ig 的浆细胞。分泌的 Igs（称为抗体）通过阻断感染性抗原与细胞受体的相互作用（通过抗原结合区）并引发导致病原体中和的效应机制（通过恒定区）来介导体液免疫的效应器阶段 (PubMed:17576170、PubMed:20176268、PubMed:22158414)。抗原结合区由一条重链的可变结构域与其相关轻链的可变结构域配对形成。每个 Ig 分子都有两个抗原结合位点，由于 V-(D)-J 重排、体细胞超突变和抗原暴露后可变域的亲和力成熟，对特定抗原具有显着的亲和力 (PubMed:17576170、PubMed:20176268、PubMed:22158414)。恒定区定义了执行不同组效应器功能的 Ig 同种型。 B 细胞通过类别转换重组使其 Ig 恒定区多样化并重新排列，这是恒定区从一种 Ig 同种型转换为另一种同种型的过程，即从 IgM 和 IgD 转换为 IgG、IgA 和 IgE (PubMed:17576170、PubMed:20176268、PubMed:22158414)。 Ig gamma-1 (IgG1) 同种型的恒定区（通过可结晶片段 Fc）与先天免疫细胞和补体系统上的受体相互作用，介导体液效应功能，包括抗体依赖性细胞毒性或吞噬作用、补体依赖性细胞毒性和炎症反应

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Related Diseases

Multiple myeloma

A malignant tumor of plasma cells usually arising in the bone marrow and characterized by diffuse involvement of the skeletal system, hyperglobulinemia, Bence-Jones proteinuria and anemia. Complications of multiple myeloma are bone pain, hypercalcemia, renal failure and spinal cord compression. The aberrant antibodies that are produced lead to impaired humoral immunity and patients have a high prevalence of infection. Amyloidosis may develop in some patients. Multiple myeloma is part of a spectrum of diseases ranging from monoclonal gammopathy of unknown significance (MGUS) to plasma cell leukemia.

Amino Acid Sequence

ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS
GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGG
PSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYN
STYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDE

FASTA format · 399 amino acids · mass 43.9 kDa

Experimental Structures

50 PDB entries

1AJ71AQK1AXS1BEY1D5B1D5I1D6V1DFB1DN21E4K1FC11FC21FCC1GAF1H3T1H3U1H3V1H3W1H3X1H3Y1HKL1HZH1I7Z1L6X1N7M1OQO1OQX1PG71T831T891VGE2DTS2GJ72I5Y2IWG2J6E2JB52JB62O5X2O5Y2O5Z2OSL2QAD2QL12QQK2QQL2QQN2QR02R562RCS

Post-Translational Modifications

•N-glycosylated. Carries predominantly biantennary complex-type glycans attached at Asn-180 residue on the Fc region of each heavy chain. Unique Fc glycan profiles found in secreted IgGs are induced in an antigen-specific way, likely programmed during B cell priming to mount an appropriate Ig effector response (PubMed:10818239, PubMed:10917521, PubMed:21768335, PubMed:22184099, PubMed:25561553, PubMed:29133956, PubMed:29445378). The core glycan is composed of two sequential N-acetylglucosamine (GlcNAc) moieties followed by a central mannose (Man) from which two additional Man residues branch out (alpha1,3 and alpha1,6 antennae) each capped with a GlcNAc. Additional sugar molecules can be added to generate over 30 possible glycans. Such sugar modifications include the addition of one fucose at the initial GlcNAc, galactose (Gal) and sialic acid (Neu5Ac) residues at antennary GlcNAc or a bisecting GlcNAc to the core Man (PubMed:10818239, PubMed:22184099, PubMed:29133956, PubMed:38383719). Variable addition of sugars account for different IgG functional states associated with antibody-dependent cellular cytotoxicity or phagocytosis and inflammatory responses such as complement activation and cytokine secretion. Fc N-glycan diversity is further enhanced by asymmetric glycan pairing on the heavy chains (PubMed:10818239, PubMed:20357243, PubMed:22184099, PubMed:29133956). Fc N-glycan sialylation is linked to anti-inflammatory effects. It regulates Fc effector functions through conformational changes leading to preferential interaction with type II Fc receptors while reducing binding to type I Fc receptors. During plasmablast response, sialylated Fc domains within immune complexes signal via FCER2/CD23 and drive the selection of B cells with high affinity for antigen (PubMed:18420934, PubMed:22184099, PubMed:25733881, PubMed:26140596). Fc Igs carrying afucosylated N-glycans preferentially activate FCGR3A, antigen-dependent cellular cytotoxicity and antitumor immunity (PubMed:12427744, PubMed:21768335, PubMed:28566370, PubMed:30061887, PubMed:36867679)
•(Microbial infection) Deglycosylation on Asn-180 by S. pyogenes EndoS or Endos2 endoglucosidases prevents interaction between immunoglobulin-gamma (IgG) and Fc receptors, impairing ability to activate the complement pathway