|Detection of PILR‑ alpha in Human Peripheral Blood Granulocytes by Flow Cytometry. Human peripheral blood granulocytes were stained with Sheep Anti-Human PILR‑ alpha PE‑conjugated Antigen Affinity-purified Polyclonal Antibody (Catalog # FAB6484P, filled histogram) or isotype control antibody (Catalog # IC016P, open histogram). View our protocol for Staining Membrane-associated Proteins.|
PILR-alpha (Paired Immunoglobulin-like, type 2 Receptor alpha) is a monomeric 44-50 kDa type I transmembrane (TM) paired receptor glycoprotein that belongs to the Ig Superfamily. It is expressed by neutrophils, monocytes, macrophages, CD14+CD1a- DC, corneal epithelium and retinal pigment cells. It is known to bind to CD99, PANP, Collectin-12, and NPDC-1. The target for PILR-alpha appears to be sialylated O-glycans. PILR-alpha also acts as a receptor for HSV and serves as a negative immunomodulator that contains an ITIM. Mature human PILR-alpha is 284 amino acids (aa) in length. It contains one V-type Ig-like domain in its extracellular region (aa 32-150), and two ITIMs in its cytoplasmic domain (aa 267-272 and 296-301). There are multiple potential splice variants. One is TM and possesses a 35 aa substitution for aa 264-303, while others are soluble, and may either show a deletion of aa 152-224 that may be coupled to the 35 aa substitution noted above, or simply exhibit a 24 aa substitution for aa 152-303. Over aa 20-196, human PILR-alpha shares only 42% aa identity with mouse PILR-alpha, and 89% aa identity with human PILR-beta.