T cells have cell-surface protein receptors {immunoglobulin superfamily, antibody}. These glycoproteins can have alpha, beta, gamma, and delta subunits. Receptor genes for these proteins are similar to immunoglobulin genes. They have similar constant, joining, diverse, and variable regions and similar promoters. Immunoglobulin superfamily includes cell-adhesion proteins {neural-cell adhesion molecule}, growth-factor receptors, and lymphokine receptors. MHC genes are similar to genes for antibodies and T-cell receptors.
Antibodies {abzyme} can act like enzymes and bind to reaction transition states. 10% of such binding affects reaction rates.
Immune-system B cells make one antibody type {allelic exclusion} and secrete it into blood.
One antibody arm can bind to one molecule, and other arm to another molecule {bispecific antibody}.
Variable antibody regions have only three parts that actually bind to antigen {complementarity determining region} (CDR). Variable regions otherwise just align CDRs. Humanized antibodies use human antibodies with CDRs from monoclonal mice.
Toxins can replace antibody regions {effector region} used to determine immunoglobulin type, to deliver agents only to correct sites.
Antibody variable regions can attach to different constant regions for different immunoglobulin types {class switching}, so all immunoglobulin types use same antibody.
Antibodies have two longer proteins {heavy chain}. Heavy chains have variable regions at arm ends, diverse region, joining region, and three constant regions. Single genes are for constant regions. Heavy chains can come from 20 diverse-region genes. Heavy chains can come from four joining-region genes. Thousands of genes code for variable regions. How regions bind together also varies.
Y
Two heavy chains join in middle to make Y shapes.
types
Heavy chains have five types: alpha, gamma, delta, epsilon, or mu.
antibody types
Heavy-chain type determines antibody type: immunoglobulinA or IgA, immunoglobulinG or IgG, immunoglobulinD or IgD, immunoglobulinE or IgE, or immunoglobulinM or IgM. IgA binds to antigens in saliva, tears, and intestines. IgG and IgM go into blood and bind to antigens, bound antigen binds to cells, and IgG and IgM activate immune-system macrophages, which eat cells with bound antigen. IgD are on B-cell surfaces. IgE starts mast cells that make histamine. Perhaps, histamine defends against parasites. Immunoglobulin-E can attack worms.
Antibodies have two shorter proteins {light chain}. Light chains have variable regions at arm ends, joining region, and constant region. Single genes are for constant regions. Light chains can come from five joining-region genes. Thousands of genes code for variable regions. How regions bind together also varies. Light chains parallel Y arms on outsides. Light chains have two types: kappa or lambda.
Immune-system genes rearrange in early infancy. Antibody gene can join second gene {joining gene} by deleting DNA between them. Joining genes join trunk gene, which determine mobility level. Joined genes determine antigen.
Immune-system genes rearrange in early infancy. Antibody gene can join joining gene by deleting DNA between them. Joining genes join gene series {trunk gene}, which determine mobility level. Joined genes determine antigen.
4-Zoology-Organ-Immune System-Protein
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Date Modified: 2022.0225