The 3B6 monoclonal antibody specifically recognizes the Insulin Receptor (IR), a glycoprotein composed of two extracellular α-subunits (130 kDa) and two transmembrane β-subunits (95 kDa). It is expressed on human hematopoietic and non-hematopoietic cells, but unlike the insulin-like growth factor receptor (IGF-IR), which is ubiquitous, the insulin receptor is restricted to major target tissues of insulin action. Upon binding insulin, the IR subunits form a heterotetramer of two α and two β subunits resulting in autophosphorylation and activation of the tyrosine kinase activity of the receptor. This ligand-receptor interaction is important in regulating cell metabolism and growth. 3B6/IR monoclonal antibody reacts similarly to anti-human IR α, clone 47-9, an α-subunit antibody.
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.