Linear epitopes

Examples of Linear epitopes in the following topics:

• Antigenic Determinants and Processing Pathways

  • Most epitopes are conformational.
  • Linear epitopes interact with the paratope based on their primary structure (shape of the protein's components).
  • A linear epitope is formed by a continuous sequence of amino acids from the antigen, which creates a "line" of sorts that builds the protein structure.
  • Antigenic determinants recognized by B cells and the antibodies secreted by B cells can be either conformational or linear epitopes.
  • Antigenic determinants recognized by T cells are typically linear epitopes.

• Monoclonal Antibodies

  • Monoclonal antibodies are monospecific antibodies that recognize one specific epitope on a pathogen.
  • Monoclonal antibodies have monovalent affinity in that they bind to the same epitope.

• Antigens and Antigen Receptors

  • Any such distinct molecular feature constitutes an epitope.
  • Therefore, most antigens have the potential to be bound by several distinct antibodies, each of which is specific to a particular epitope.
  • Using the "lock and key" metaphor, the antigen itself can be seen as a string of keys - any epitope being a "key" - each of which can match a different lock.
  • Different antibody idiotypes, each having distinctly formed complementarity determining regions, correspond to the various "locks" that can match "the keys" (epitopes) presented on the antigen molecule.

• Antibodies: Classes and Affinity Maturation

  • Humans generate an estimated 10 billion different antibodies, each capable of binding a distinct antigen epitope.
  • A group of antibodies can be called monovalent (or specific) if they have affinity for the same epitope, or for the same antigen (but potentially different epitopes on the molecule), or for the same strain of microorganism (but potentially different antigens on or in it).
  • In contrast, monoclonal antibodies are monovalent for the same epitope.

• Maturation of B Cells

  • All B cells derive from a particular cell, and thus, the antibodies their differentiated progenies produce can recognize and/or bind the same specific surface components composed of biological macromolecules (epitope) of a given antigen.
  • Most of such B cells differentiate into plasma cells that secrete antibodies into blood that bind the same epitope that elicited proliferation in the first place.
  • A small minority survives as memory cells that can recognize only the same epitope.

• Graft Rejection and Tissue Typing

  • If the antibodies recognize their epitope on the MHC, then complement activation occurs and the cell will be osmotically lysed.

• Complete Antigens and Haptens

  • In this case, the hapten acts as the epitope for the antigen, which binds to the antibodies without causing a response.

• Myocarditis and Endocarditis

  • Streptococcal M protein and coxsackievirus B have regions (epitopes) that are immunologically similar to cardiac myosin.

• Structure and Function of Antibodies

  • Each tip of the "Y" of an antibody contains a paratope (a structure analogous to a lock) that is specific for one particular epitope (similarly analogous to a key) on an antigen, allowing these two structures to bind together with precision.

• Clonal Selection and T-Cell Differentiation

  • Here, the body's own epitopes are presented to the infant lymphocytes; those that react are recognized as auto-reactive and destroyed before they (and their future cloned daughter cells) can leave and wreak havoc in the body.