Immunoglobulin Fine Structure

The structure of the immunoglobulin molecule is determined by the primary, secondary, tertiary, and quaternary organization of the protein. The primary structure, the amino acid sequence, accounts for the variable and constant regions of the heavy and light chains. The secondary structure is formed by folding of the extended polypeptide chain y Molecular Visualization

An Introduction to Immunoglobulin Structure


Chain composition of the five immunoglobulin classes in humans

Heavy Light Molecular

Class chain Subclasses chain formula

IgG y


IgE e None

IgD 8 None k or X

y2K2 y2X2 (^2K2)n

82K2 82X2

back and forth upon itself into an antiparallel ß pleated sheet (Figure 4-4). The chains are then folded into a tertiary structure of compact globular domains, which are connected to neighboring domains by continuations of the polypeptide chain that lie outside the ß pleated sheets. Finally, the globular domains of adjacent heavy and light polypeptide chains interact in the quaternary structure (Figure 4-5), forming functional domains that enable the molecule to specifically bind antigen and, at the same time, perform a number of biological effector functions.

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Essentials of Human Physiology

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    Is immunoglobulin secondary, quaternary?
    9 months ago

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