The 108928 monoclonal antibody specifically recognizes the Mer tyrosine kinase (Mer or MerTK). Mer is a single-pass type I transmembrane glycoprotein that is encoded by Mertk (c-mer proto-oncogene tyrosine kinase) and is also known as Eyk, Nyk, Tyro 12, or Nmf12. Mer is comprised of an extracellular region with two immunoglobulin (Ig)-like domains and two fibronectin type III (FNIII) domains, a transmembrane segment and a conserved intracellular tyrosine kinase domain. Tyro-3, Axl, and Mer constitute the TAM subfamily of receptor tyrosine kinases (RTK). Mer is variably expressed by multiple cell types including monocytes, macrophages, dendritic cells, NK cells, platelets, and epithelial cells including retinal pigment epithelial cells. Mer binds to the vitamin K-dependent Growth arrest-specific protein 6 (Gas6) and to Protein S (ProS) through its extracellular Ig-like domains. Ligand binding leads to receptor dimerization, and autophosphorylation of tyrosine residues within the cytoplasmic Mer domains. This results in the activation of downstream signaling pathways that control cellular adhesion, aggregation, phagocytosis/efferocytosis, proliferation, survival, and migration. Through these activities, Mer plays major roles involved in development and in the regulation of hematopoiesis and immunity. Abnormal expression of Mer has been observed in various cancers and by certain tumor cell lines.
The antibody was conjugated to BD Horizon BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).