Final answer:
Yes, B cells remove gene segments encoding the μ constant region and juxtapose the rearranged variable region with other gene segments encoding different constant regions. This recombination is performed by DNA recombinase, and allows for diversity in the body's immunoglobulin response. Further maturity allows for isotype switching that varies the constant region while preserving antigen specificity.
Step-by-step explanation:
Antibody Diversity and B Cell Development
The student is asking whether B cells can remove gene segments encoding the μ constant region and juxtapose the rearranged variable region with a gene segment encoding a different constant region. This process is indeed a foundation of immune system adaptability. During the maturation of B cells, gene rearrangements occur, involving the excision of V (variable), D (diversity), and J (joining) segments. The enzyme responsible for this random excision is DNA recombinase. This recombination event occurs at the DNA level creating unique sequences which code for the variable regions of antibodies, and subsequent RNA processing further refines the gene sequence to produce a unique antigen-binding site. These unique variable regions then pair with constant regions to give rise to diverse antibody molecules.
Over time, some mature B cells will undergo a process called isotype switching, which effectively allows the cell to produce antibodies with different constant regions, providing the ability to respond to different types of antigens more effectively. This ability to alter the constant region does not change the specificity for the antigen; the variable region remains the same, keeping the ability to bind the same antigen.
In summary, the immense diversity of the B cell receptor repertoire is achieved through both the recombination of V(D)J segments and, later in B cell development, through isotype switching, which involves changes in the constant region of immunoglobulins, allowing for the generation of different classes of antibodies that retain their antigen specificity.