Follicle Stimulating Hormone Beta (FSHb) is a subunit of Follicle - Stimulating Hormone (FSH). As a key component, FSHb confers the hormone's specificity. Along with the the alpha chain CGA, it forms FSH. In the body, FSH plays a crucial role in the reproductive system. In females, it stimulates follicular growth and maturation in the ovaries. In males, it is involved in spermatogenesis in the testes. Mutations in the FSHb gene can lead to reproductive disorders.To detect the biological activity of FSHb a functional ELISA assay was conducted to detect the interaction of recombinant rat FSHb and recombinant mouse CGA. Briefly, FSHb was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to CGA-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-FSHb pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630nm immediately. The binding activity of recombinant recombinant rat FSHb and recombinant mouse CGA was shown in Figure 1, the EC50 for this effect is 0.112ug/mL.