C H A P T E R 3 5 , F I G U R E 4

Microbe destruction by neutrophils and antibody-dependent, cell-mediated cytotoxic-

ity. (A) Neutrophils recognize and attack antibody-tagged microorgansims by a mechanism called antibody-depen-

dent, cell-mediated cytotoxicity (ADCC). In this defense mechansim, microbes “tagged” by antibodies are destroyed

by a respiratory burst of 0 3", H20 2, and NO produced by the attacking neutrophils. (B) In a similar way, natural killer

(NK) cells recognize antibody-tagged virus-infected cells and tumor cells.

C H A P T E R 3 5 , F I G U R E 5

Structural motif of the immunoglobulin

family. Each domain of the immunoglobulin or other molecule of the

immunoglobulin family is composed of a collection of p strands that

form a globular structure. Colors indicate different p strands. There are

seven strands in the constant region domains that form two p sheets; one

sheet contains three antiparallel strands and the other four antiparallel

strands. The orientation illustrates the two sheets that together create the

P sandwich or immunoglobulin fold.

C H A P T E R 3 5 , F IG U R E 6

Pairs of immunoglobulin motif structures

(see Figure 35-7) connected by a “tether” polypeptide that creates a flexible

fold. The disulfide bridges that connect the P sheets of the p sandwich are

shown as yellow space-filling residues. Each IgG molecule contains six such

folds arranged so that a heavy and light chain folds partially wrap around

each other (Figure 35-7 B, C). The ribbon model shown is from an x-ray

crystallographic structure of a Fab fragment. The figure is derived from the

coordinates published in the Protein Data Bank file, 2FPB.