Proteins can be for protection {immunity}|. Antigen binding to beta-lymphocyte surface triggers process that creates plasma cells. Plasma cells specialize to make antibody to antigen.
Antigens can enter body. Immunoglobulin proteins {antibody}| bind antigens, so body can remove foreign molecules. Antibodies bind to antigens by hydrogen bonds, van der Waals forces, and ionic bonds. Antibody-connecting subunits can cross plasma membrane and bind to cells.
structure
Antibodies have three subunits. Two subunits can bind to one antigen each. One subunit connects two binding subunits to make Y-shaped structure. Antibodies have two light protein chains and two heavy protein chains, linked by disulfide bonds. Light chains are at Y tips. All antibodies have kappa or lambda light chain but different heavy-chain constant regions. Heavy chains are in arms and base of Y. Light and heavy chains have variable end and constant end. Several hundred genes code variable regions, making millions of different antibodies. About 100,000,000 different antibody shapes can exist.
precipitation
When one antibody binds to two antigens, complex becomes insoluble. Bound molecules precipitate from solution, and then cell phagocytes eat them.
Five proteins {immunoglobin}| affect immunity. IgA is in secretions. Immune system makes IgM first. IgG increases as IgM decreases. IgE is for allergies. IgD is another immunoglobin.
Large molecules {antigen}| can enter body from outside.
Antigens have regions {epitope}| where other molecules can bind.
Small molecules {hapten} can bind to epitope.
Protein groups {complement, protein} can lyse cells if antibodies bind to cells.
Genes {joint gene} {J gene} can code for connections between light and heavy chains.
5-Chemistry-Biochemistry-Protein-Kinds
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Date Modified: 2022.0225