Final answer:
Rearrangements at the light chain locus involve the excision of most V and J segments by DNA recombinase, and RNA splicing results in over 106 VJ combinations, giving each antibody a unique variable region for antigen binding.
Step-by-step explanation:
Rearrangements take place on one light chain locus during the maturation of germ-line B cells, creating a vast diversity of antibodies. The variable region of the light chain gene consists of 40 variable (V) and five joining (J) segments. An enzyme called DNA recombinase facilitates a process in which most of the segments are excised, leaving one V segment spliced to one J segment.
During RNA processing, splicing excludes all segments except for one V and one J, leading to the possibility of over 106 different VJ combinations. This diversity equips each antibody with a unique variable region capable of binding various antigens, crucial for effective immune responses. However, the constant domain of the antibody, which does not partake in antigen binding, remains the same across all antibodies.