Immunoglobulin molecules

Fc function (portion of fully functional immunoglobulin molecule) prekailikrein activator, <35 lU/mL HBsAs antibody, >1 lU/g normal subclass distribution osmolality, <280 mosmol 4 to 7.4 pH. Ref. 221. 

Chothia, C., et al. Domain association in immunoglobulin molecules. The packing of variable domains. /. Mol. Biol. 186 651-663, 1985. 

The constant regions of the immunoglobulin molecules, particularly the C 2 and 0 3 (and C 4 of IgM and IgE), which constitute the Fc fragment, are responsible for the class-specific effector functions of the different immunoglobulin molecules (Table 50-7, bottom part), eg, complement fixation or transplacental passage. 

The L chains and H chains are synthesized as separate molecules and are subsequently assembled within the B cell or plasma cell into mature immunoglobulin molecules, all of which are glycoproteins. 

Fc Crystallizable fraction of immunoglobulin molecule Fey Receptor for Fc portion of IgG FeyRI Ig Fc receptor I also known as CD64... 

A second type of occultation concerns the relations that exist between biomolecules. In the same way that the antibody nature of an immunoglobulin molecule becomes evident only when its complementary antigen has been recognized, the epitope nature of a set of amino acids in a protein can... 

Bach, M.A, Kohler, H. and Levitt, D. (1983) Binding of phosphorylcholine by non-immunoglobulin molecules on mouse B cells. Journal of Immunology 131, 365-371. 

Add 0.3 mg of sulfo-NHS-SS-biotin (Thermo Fisher) to each ml of the antibody solution. To measure out small amounts of the biotinylation reagent, it may be first dissolved in water at a concentration of at least 1 mg/ml. Immediately transfer the appropriate amount to the antibody solution. This level of sulfo-NHS-SS-biotin addition represents about an 8-fold molar excess over the amount of antibody present. This should result in a molar incorporation of approximately 2-4 biotins per immunoglobulin molecule. 

Antigen binding by a complementary immunoglobulin molecule on the surface of B cells starts a process of cellular internalization of the foreign substance by pinocytosis. Once internalized by endosomes, systematic processing of the antigen takes place which breaks it down into smaller components. 

The most common carrier proteins in use today are keyhole limpet hemocyanin (KLH MW 4.5 X 105 to 1.3 X 107), BSA (MW 67,000), aminoethylated (or cationized) BSA (cBSA), thyroglobulin (MW 660,000), ovalbumin (OVA MW 43,000), and various toxoid proteins, including tetanus toxoid and diphtheria toxoid. Other proteins occasionally used include myoglobin, rabbit serum albumin, immunoglobulin molecules (particularly IgG) from bovine or mouse sera, tuberculin purified protein derivative, and synthetic polypeptides such as poly-L-lysine and poly-L-glutamic acid. 

The heavy chains of each immunoglobulin molecule are identical. Depending on the class of immunoglobulin, the molecular weight of these subunits ranges from about 50,000 to around... 

Figure 1.13. Schematic representation of an IgA molecule. Each IgA molecule comprises immunoglobulin molecules joined to each other via a J chain. The heavy chains possess three constant regions (Co1 Cce). The secretory chain (SC) is secreted by epithelial cells and binds to the IgA dimer via disulphide bonds (indicated by wriggly lines).

The structure of MHC. In the context of antigen recognition by T cells, we are primarily concerned with class I and II MHC molecules. Class III MHC are essentially a part of the complement system. Class I molecules are made up of transmembrane heavy-chain peptide, which is noncovalently associated with the B2 microglobulin (B2m) molecule. Class II, on the other hand, is composed of two smaller transmembrane peptide chains, a and p. The peptides are arranged in domains that are of comparable size to those of the immunoglobulin molecules. 

So-called, B lymphocytes, which constitute about 20% of the total lymphocyte population in the blood, have only one major function which is to synthesize and secrete immunoglobulin antibodies. Following an antigenic challenge, B cells develop into plasma cells whose role is to produce specific immunoglobulin molecules in what is known as the humoral arm of the immune response. 

---