BLNK Gene - B-Cell Linker Protein: Function, Mutations, and Disease Associations

BLNK (B-cell linker protein) is a cytoplasmic adaptor protein essential for B-cell receptor (BCR) signaling. It bridges the BCR-associated kinases SYK and BTK to downstream effectors such as PLCG2, leading to calcium mobilization, MAPK activation, and transcriptional regulation. BLNK is critical for B-cell development, maturation, and immune response. Mutations in BLNK cause autosomal recessive agammaglobulinemia type 4 (AGM4), characterized by early-onset recurrent infections and absence of mature B cells.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• B cell receptor signaling pathway (KEGG hsa04662)

• Primary immunodeficiency (KEGG hsa05340)

• Fc gamma R-mediated phagocytosis (KEGG hsa04666)

BLNK is a 456-amino-acid adaptor protein with an N-terminal leucine zipper motif, a central proline-rich region, and a C-terminal SH2 domain. It lacks intrinsic enzymatic activity but serves as a scaffold for SYK, BTK, PLCG2, and GRB2. Upon BCR engagement, BLNK is phosphorylated by SYK, creating docking sites for downstream effectors. This protein is predominantly expressed in B cells and is essential for B-cell maturation and antibody production.