Anti-PTK4 antibodies are used in antigen-specific immunodetection in biological samples. The target PTK4 is a known alias name of the protein TXK tyrosine kinase, encoded by the TXK gene in humans. This 527-amino acid residue protein is a type of non-receptor tyrosine kinase that plays a redundant role with ITK in regulation of the adaptive immune response. It is localized to the cell membrane, nucleus, and cytoplasm of the cell and features palmitoylated and phosphorylated post-translational modifications. In terms of tissue expression, it is reported to be expressed in T-cells and some myeloid cell lines. Other synonyms for PTK4 include BTKL and PSCTK5.