Immunology - Immunoglobulin

Immunoglobings (Igs)

- these cells produce a vast range of antigen specificities -each B cell producing immunoglobulins of single specificity

How does the body fight the wide range of pathogens?

-The adaptive immune system's lymphocytes have evolved to recognize a great variety of antigens from bacteria, viruses and other disease causing organisms.

An antigen

-any molecule or part of a molecule that is specifically recognized by the highly specialized recognition proteins of lymphocytes

lgG

-count for 70 to 80 % of the entire immunoglobulin pool of the body -target pathogens such as bacteria, viruses, and worms -attaches to an antigen, while the opposite end binds with a phagocyte white cell including macrophages, neutrophils, and natural killer cells, and destroy the antigen. - It is the smallest of the IG molecules allowing it to easily migrate to the tissues of the body -only 45% found in the blood

A given immunoglobulin

-has either Κ chains or λ chains, never one of each -No functional difference has been found between antibodies having λ or Κ light chains, and either type of light chain can be found in antibodies of any of the five major classes

antibody molecule has two separate functions:

-one is to bind specifically to the pathogen or its products that have elicited the immune response; the other is to recruit other cells and molecules to destroy the pathogen once the antibody has bound -For example, binding by antibodies can neutralize viruses and mark pathogens for destruction by phagocytes and complement

IgE

-responsible for allergic symptoms and parasitic -lgE comes into contact with one of the antigens ,the mast cells and basophil will release histamine molecules causing the inflammatory symptoms known an allergic reaction

The amino acid sequences of many immunoglobulin heavy and light chains have been determined and reveal two important features of antibody molecules.

First, each chain consists of a series of similar, although not identical, sequences, each about 110 amino acids long. Each of these repeats corresponds to a discrete, compactly folded region of protein known as an immunoglobulin domain, or Ig domain.

Distortions of the 2:1 human ratio can result in

For example, an abnormally high level of λ light chains in a person might indicate the presence of a B-cell tumor that is producing λ chains.

IgA

Found in mucous, saliva, tears, and breast milk. Protects against pathogens such as bacteria,fungus & parasitic worms

Most of the antibodies circulating in the body are

IgG

Which immunoglobulin type is the lightest?

IgG

____ antibodies consist of four polypeptide chains

IgG antibody

Which immunoglobulin type is the heaviest?

IgM

Which complement system does it work with specifically? IgM

IgM activates the classical pathway complement system only after binding to cell-surface antigens.

Why does IgM usually go out first during the early stages of infection?

IgM is the first antibody to be produced in response to infection since it does not require 'class switch' to another antibody class. However, it is only synthesized as long as antigen remains present because there are no memory cells for IgM.

T/F the heavy chain has more constant regions than the light chain.

The Ig molecule consists of two polypeptide chains, a heavy (H) and a light (L) chain, each of which is composed of two regions, a constant region (C) and a variable region (V)

T/F the heavy chain does not have a variable region.

The heavy chain's variable region (VH) differs depending on the B cell that produced it but is the same for all antibodies produced by a single B cell or B cell clone.

Which chain is hinged?

The hinge region is a stretch of heavy chains between the Fab and Fc portions. Its unique structure and position provide segmental flexibility, which is essential for normal functioning of antibodies (e.g., for crosslinking two antigens or binding two antigenic determinants on the same antigen molecule).

Why is it so heavy?

The largest immunoglobulin with 10 paratopes.

What joins the two heavy and two light chains together?

The two heavy chains are linked to each other by disulfide bonds and each heavy chain is linked to a light chain by a disulfide bond. In any given immunoglobulin molecule, the two heavy chains and the two light chains are identical, giving an antibody molecule two identical antigen-binding site

There are five different classes of immunoglobulins, distinguished (c region)

These are known as immunoglobulin M (IgM), immunoglobulin D (IgD), immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin E (IgE).

The ends of the two arms of the Y—the V regions

are involved in antigen binding, and they vary in their detailed structure between different antibody molecules.

A membrane-bound form of immunoglobulin on the B-cell surface serves as the cell's receptor for antigen and is known

as the B-cell receptor (BCR)

IgM

first antibody produced in an immune response -early responders, functions to eliminate pathogens early on in the attack before there are sufficient levels of IgG -macroglobulin, are the largest of the immunoglobulins

IgD

found on the surface of B cells,small portion of free-flowing membranes found in the plasma activation of basa fills and mast cells to attack invading microbes

The multiple heavy-chain C domains are numbered

from the amino-terminal end to the carboxyl terminus; for example, CH1, CH2, and so on.

whereas in the antibody it is a

hydrophilic sequence that allows secretion.

B cells the proteins are

immunoglobulins (Igs)

In the B-cell receptor, the carboxyl terminus

is a hydrophobic amino acid sequence that anchors the molecule in the membrane

The stem of the Y—the C region—

is far less variable and is the part that interacts with effector molecules and cells.

The second important feature of amino acid sequences of many immunoglobulin

is that the amino-terminal amino acid sequences of the heavy and light chains vary greatly between different antibodies. The variability is limited to approximately the first 110 amino acids, corresponding to the first Ig domain, whereas the remaining domains are constant between immunoglobulin chains of the same isotype.

Two types of light chains are found in antibodies

lambda (λ) and kappa (Κ)

The amino-terminal variable Ig domains (V domains)

of the heavy and light chains (VH and VL, respectively) together make up the V region of the antibody and determine its antigen-binding specificity

innate immune response

rapid but relatively nonspecific immune response -bodys inital defense against infection -works to control pathogens

These different classes of antibodies are known as isotypes

they include IgM, IgD, IgG, IgA, and IgE

The Y-shaped antibody molecules

this structure is formed and allows the antibody molecule to perform its dual tasks of binding to a wide variety of antigens while also binding to effector molecules and to cells that destroy the antigen

each immunoglobulin molecule is made up of

two hinged heavy chains (green) and two light chains (yellow) joined by disulfide bonds so that each heavy chain is linked to a light chain and the two heavy chains are linked together.

The backbones of an IgG antibody is made up of _____ chains

two identical heavy chains and two identical light chains

"Immunoglobulin molecules are composed of

two types of protein chains: heavy chains and light chains

What are the two types of chains that make up the antibody molecule?

two types of protein chains: heavy chains and light chains.