Final answer:
The first stage of T-cell receptor gene rearrangement in α:β T cells is the recombination of the Vβ segment with the Dβ segment (Vβ→ Dβ), which is crucial for creating the diversity in the beta chain of the TCR for antigen recognition.
Step-by-step explanation:
The first stage of T-cell receptor (TCR) gene rearrangement in α:β T cells is c. Vβ→ Dβ. During this process, which occurs during the development of the functional TCR in the thymus, a gene segment known as Variable Beta (Vβ) is recombined with a segment known as Diversity Beta (Dβ) to code for the variable region of the β chain. This step is followed by the joining of Dβ and Joining Beta (Jβ) segments. For the α chain, a Variable Alpha (Vα) segment combines with a Joining Alpha (Jα) segment without a diversity segment intervening.
This genetic rearrangement process is crucial as it contributes to the diversity of the T-cell receptor, allowing the immune system to recognize a vast array of antigens. The T-cell receptor is composed of an α and a β chain, each with variable (V), joining (J), and constant (C) regions, while the β chain also includes a diversity (D) region. The resulting diversity from the combination of different V, D, and J segments enables the TCR to be highly specific in antigen recognition.