Regions, immunoglobulin

Q Fibronectin type III domain (motif I) Q MLCK region [] Immunoglobulin domain (motif II) Q Interdomain... 

Chothia C, A M Lesk, A Tramontano, M Levitt, S Smith-Gill, G Air, S Sheriff, E A Padlan and D Davies 1989. Conformations of Immunoglobulin Hypervariable Regions. Nature 342 877-883. 

C Chothia, AM Lesk. Canonical structures for the hypervariable regions of immunoglobulins. J Mol Biol 196 901-917, 1987. 

Figure 13.24 Six subfamilies of receptor tyrosine kinases involved in cell growth and differentiation. Only one or two members of each subfamily are indicated. Note that the tyrosine kinase domain is interrupted by a "kinase insert region" in some of the subfamilies. The functional significance of the cysteine-rich and immunoglobulin-like domains is unknown.

Figure 1S.6 Enzymatic cleavage of immunoglobulin IgG. The enzyme papain splits the molecule in the hinge region, yielding two Fab fragments and one Fc fragment.

The residues not in the framework region form the loops between the p strands. These loops may vary in length and sequence among immunoglobulin chains of different classes but are constant within each class the sequence of the loops is invariant. The functions of these loops are not known, but they are probably involved in the effector functions of antibodies. When an antibody-antigen complex has been formed, signals are... 

The class 1 MHC structure is divided into two globular regions (Figure 15.18). One region is built up from the two immunoglobulin-like domains a3... 

T-cell receptors have variable and constant immunoglobulin domains and hypervariable regions... 

IgG antibody molecules are composed of two light chains and two heavy chains joined together by disulfide bonds. Each light chain has one variable domain and one constant domain, while each heavy chain has one variable and three constant domains. All of the domains have a similar three-dimensional structure known as the immunoglobulin fold. The Fc stem of the molecule is formed by constant domains from each of the heavy chains, while two Fab arms are formed by constant and variable domains from both heavy and light chains. The hinge region between the stem and the arms is flexible and allows the arms to move relative to each other and to the stem. 

Class 1 and class II MHC molecules bind peptide antigens and present them at the cell surface for interaction with receptors on T cells. The extracellular portion of these molecules consists of a peptide-binding domain formed by two helical regions on top of an eight-stranded antiparallel p sheet, separated from the membrane by two lower domains with immunoglobulin folds. These domains are differently disposed between the two protein subunits in class I and class II molecules. 

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