The 4FR6D3 monoclonal antibody specifically recognizes CD334 which is also known as Fibroblast growth factor receptor 4 (FGFR4), Tyrosine kinase related to fibroblast growth factor receptor (TKF), or JTK2. CD334 is a ~110 kDa type I transmembrane glycoprotein that belongs to the fibroblast growth factor receptor (FGFR) in the Ig superfamily (IgSF). The ligand-binding extracellular domain has three immunoglobulin-like C2-type domains followed by a transmembrane region and a cytoplasmic tail which contains a tyrosine kinase domain. CD334 serves as a high affinity receptor that dimerizes upon binding to fibroblast growth factors including FGF-1, -2, -4, -6, -8, -9, -16, -17, -18, and -19. This cell surface receptor tyrosine kinase is widely expressed on epithelial cells, fibroblasts and skeletal muscle cells and plays a role in the proliferation, differentiation, migration, and survival of these different cell types. Abnormal expression and activity of CD334 has been associated with a number of different cancers.
The antibody was conjugated to BD Horizon™ BUV661 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.