The SE5A5 monoclonal antibody specifically binds to a common epitope on CD172a/SIRPα (90 kDa) and CD172b/SIRPβ1 (50 kDa). These transmembrane glycoproteins are members of the Signal Regulatory Protein (SIRP) family that, in turn, belongs to the Immunoglobulin superfamily. The SIRP family is comprised of two subgroups, SIRPα and SIRPβ that are distinguished by the presence (α) or absence (β) of a cytoplasmic domain containing two immunoreceptor tyrosine-based inhibition motifs (ITIM). CD172a/SIRPα is expressed on CD34+ stem/progenitor cells, cardiomyocytes, monocytes, macrophages, granulocytes, dendritic cells, and in the central nervous system. It binds to CD47 and is implicated in mediating inhibitory signals via the ITIM/SHP-2 association. CD172b/SIRPβ1 does not possess a cytoplasmic domain but instead the transmembrane domain contains a positively-charged residue that can interact with another transmembrane protein, DAP-12/KARAP. DAP-12 has two immunoreceptor tyrosine-based activation motifs (ITAM) within its cytoplasmic domain that are thought to link CD172b to cellular activation signaling. CD172b is expressed on myeloid cells, including peripheral blood monocytes and granulocytes. It is not expressed on CD34+ cells. CD172a and CD172b have complementary roles in signal regulation and may work together in tuning certain cellular responses to stimuli.
This antibody is conjugated to BD Horizon™ BV605 which is part of the BD Horizon Brilliant™ Violet family of dyes. With an Ex Max of 407-nm and Em Max of 602-nm, BD Horizon BV605 can be excited by a violet laser and detected with a standard 610/20-nm filter set. BD Horizon BV605 is a tandem fluorochrome of BD Horizon BV421 and an acceptor dye with an Em max at 605-nm. Due to the excitation of the acceptor dye by the green (532 nm) and yellow-green (561 nm) lasers, there will be significant spillover into the PE and BD Horizon PE-CF594 detectors off the green or yellow-green lasers. BD Horizon BV605 conjugates are very bright, often exhibiting brightness equivalent to PE conjugates and can be used as a third color off of the violet laser.