TNFRSF13B, also known as TACI, is a transmembrane receptor protein found predominantly on the surface of B cells, which are an important part of the immune system. It was originally discovered because of its ability to interact with calcium-modulator and cyclophilin ligand (CAML). It was later found to play a crucial role in humoral immunity by interacting with two members of the TNF family. It controls T cell-independent B cell antibody responses, isotype switching, and B cell homeostasis. Recombinant human TNFRSF13B protein, fused to His-tag at N-terminus, was expressed in E.coli.