TCR Diversity Is Generated Like Antibody Diversity but Without Somatic Mutation

Although TCR germ-line DNA contains far fewer V gene segments than Ig germ-line DNA, several mechanisms that operate during TCR gene rearrangements contribute to a high degree of diversity among T-cell receptors. Table 9-3 (page 210) and Figure 9-8 (page 211) compare the generation of diversity among antibody molecules and TCR molecules.

Rearranged a-chain gene

Encoded domains

Rearranged a-chain gene

Variable domain (Va or Vp)

Leader

Variable domain (Va or Vp)

Rearranged P -chain gene

FIGURE 9-7

Connecting sequence Constant Trans- tail domain membrane (Ca or Cp) region

H Tm CT

CDR1 CDR2 CDR3

Schematic diagram of rearranged a^-TCR genes showing the exons that encode the various domains of the ap T-cell receptor and approximate position of the CDRs. Junctional diversity (vertical arrows) generates CDR3 (see Figure 9-8). The structures of the rearranged 7- and 8-chain genes are similar, although additional junctional diversity can occur in 8-chain genes.

CLINICAL FOCUS

CLINICAL FOCUS

T-Cell Rearrangements as Markers for Cancerous Cells

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Essentials of Human Physiology

Essentials of Human Physiology

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