TNFRSF13B

TNFRSF13B Full Name

tumor necrosis factor receptor superfamily, member 13B

TNFRSF13B Introduction

TNFRSF13B is a gene located on human chromosome 17 (17p11.2) that encodes the Transmembrane Activator and CAML Interactor (TACI) protein. TACI is a type III transmembrane receptor belonging to the tumor necrosis factor receptor superfamily (TNFRSF). It is primarily expressed on the surface of mature B lymphocytes and a subset of innate immune cells. Structurally, it possesses extracellular cysteine-rich domains (CRDs) essential for ligand binding and intracellular motifs that recruit adaptor proteins, most notably the TRAF family (TRAF2, TRAF5, TRAF6), to initiate downstream signaling cascades.

Figure 1. Strcuture of TNFRSF13B.

The TNFRSF13B gene is located on human chromosome 17, specifically within the Smith-Magenis syndrome region, and it provides instructions for synthesizing the TACI protein. The TACI protein is a type I transmembrane glycoprotein that is predominantly expressed on the surface of B lymphocytes, a key type of immune cell involved in antibody production, as well as in other immune-related tissues such as the spleen and lymph nodes—tissues where its expression levels are relatively high compared to other parts of the body. Structurally, TACI contains extracellular cysteine-rich domains that enable it to bind to specific ligand molecules, including B cell Activating Factor (BAFF) and A Proliferation-Inducing Ligand (APRIL), both of which are critical for regulating B cell activity. Additionally, its intracellular domain facilitates interactions with other proteins, such as calcium-modulator and cyclophilin ligand (CAML), to initiate downstream signaling pathways that influence immune cell behavior.

The core biological function of TNFRSF13B revolves around its role in regulating B cell homeostasis, maturation, and function, thereby maintaining the balance of the humoral immune system. Upon binding to its ligands BAFF and APRIL, TACI activates a series of intracellular signaling cascades that promote the activation of transcription factors such as NFAT, AP1, and NF-kappa-B—molecules that control the expression of genes involved in immune responses. This activation process is essential for driving B cell differentiation into plasma cells, which are responsible for producing and secreting antibodies, as well as for facilitating immunoglobulin class switching, a process that allows B cells to produce different types of antibodies tailored to specific pathogens. Furthermore, TNFRSF13B plays a dual role in regulating B cell proliferation: it not only supports the survival and maturation of functional B cells but also exerts a negative regulatory effect on B cell proliferation to prevent abnormal immune activation that could lead to autoimmune disorders

Alternate Names for TNFRSF13B

TNFRSF13B; tumor necrosis factor receptor superfamily, member 13B; CVID; RYZN; TACI; CD267; CVID2; IGAD2; TNFRSF14B; tumor necrosis factor receptor superfamily member 13B; tumor necrosis factor receptor 13B; transmembrane activator and CAML interactor;