T cell receptor (TCR)

Definition

The T cell receptor (TCR) is a complex of membrane-bound proteins expressed on the surface of T cells that recognizes and binds to specific antigenic peptides presented by major histocompatibility complex (MHC) molecules on antigen-presenting cells. This interaction is crucial for the activation and function of T cells in the adaptive immune response.

5 Must Know Facts For Your Next Test

1. The T cell receptor is composed of two transmembrane glycoprotein chains, typically an alpha (α) chain and a beta (β) chain, which form a heterodimer.
2. The variable regions of the TCR α and β chains are responsible for recognizing and binding to specific antigenic peptides presented by MHC molecules on antigen-presenting cells.
3. The TCR-MHC-peptide interaction, along with co-stimulatory signals, triggers a cascade of intracellular signaling events that lead to T cell activation and the initiation of the adaptive immune response.
4. The diversity of the TCR repertoire is generated through the random rearrangement of variable (V), diversity (D), and joining (J) gene segments during T cell development, allowing T cells to recognize a wide range of antigenic peptides.
5. The TCR-MHC-peptide interaction is highly specific, with each TCR recognizing a unique combination of MHC molecule and antigenic peptide, ensuring the targeted and efficient activation of T cells.

Review Questions

• Explain the role of the T cell receptor (TCR) in the recognition of antigenic peptides presented by MHC molecules on antigen-presenting cells.
  • The T cell receptor (TCR) is a complex of membrane-bound proteins expressed on the surface of T cells that recognizes and binds to specific antigenic peptides presented by major histocompatibility complex (MHC) molecules on antigen-presenting cells. This TCR-MHC-peptide interaction is crucial for the activation and function of T cells in the adaptive immune response. The variable regions of the TCR α and β chains are responsible for recognizing and binding to the specific antigenic peptide-MHC complex, triggering a cascade of intracellular signaling events that lead to T cell activation and the initiation of the adaptive immune response.
• Describe the relationship between the T cell receptor (TCR), major histocompatibility complex (MHC), and antigen-presenting cells (APCs) in the context of T cell activation.
  • The T cell receptor (TCR) plays a central role in the recognition of antigenic peptides presented by major histocompatibility complex (MHC) molecules on antigen-presenting cells (APCs). The TCR-MHC-peptide interaction is highly specific, with each TCR recognizing a unique combination of MHC molecule and antigenic peptide. This interaction, along with co-stimulatory signals, triggers a cascade of intracellular signaling events that lead to T cell activation and the initiation of the adaptive immune response. Antigen-presenting cells, such as dendritic cells, macrophages, and B cells, are responsible for capturing, processing, and presenting antigenic peptides to T cells via MHC molecules, enabling the T cells to recognize and respond to specific pathogens or foreign substances.
• Analyze the importance of the diverse T cell receptor (TCR) repertoire in the adaptive immune response.
  • The diversity of the T cell receptor (TCR) repertoire is crucial for the adaptive immune system's ability to recognize a wide range of antigenic peptides. This diversity is generated through the random rearrangement of variable (V), diversity (D), and joining (J) gene segments during T cell development, allowing T cells to express a vast array of unique TCRs. The high specificity of the TCR-MHC-peptide interaction ensures that each T cell can recognize a specific combination of MHC molecule and antigenic peptide. This diverse TCR repertoire enables the adaptive immune system to mount a targeted and efficient response against a wide variety of pathogens and foreign substances, ensuring the body's effective defense against disease.

Related terms

Major Histocompatibility Complex (MHC):

The major histocompatibility complex is a group of genes that encode cell surface proteins responsible for presenting antigenic peptides to T cells, enabling the immune system to distinguish self from non-self.

Antigen-Presenting Cells (APCs):

Antigen-presenting cells are specialized cells, such as dendritic cells, macrophages, and B cells, that capture, process, and present antigenic peptides to T cells via MHC molecules, initiating the adaptive immune response.

T Cell Activation: T cell activation is the process by which a T cell becomes stimulated and primed to carry out its effector functions, such as cytokine production or cytotoxic killing, in response to the recognition of an antigenic peptide presented by an MHC molecule.