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.
4-Zoology-Organ-Immune System-Protein-Antibody
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Date Modified: 2022.0225