Ly6/PLAUR Domain Containing Protein 3 (LYPD3)

The deduced 346-amino acid protein shares 81.8% amino acid identity with rat C4.4a and has 6 N-glycosylation sites and a potential glycosylphosphatidylinositol (GPI)-anchoring sequence. C4.4A shares 43.5% identity with uPA receptor (UPAR, or PLAUR), and both proteins have 3 domains, a conserved uPA (PLAU) cleavage site within the linker region between domains 1 and 2, and complete conservation of all 17 cysteines. Northern blot analysis and RT-PCR of several tissues detected C4.4A expression in placenta and skin. Weak expression was detected in esophagus and peripheral blood mononuclear cells, but not in peripheral blood-derived T cells. C4.4A was expressed in a variety of tumor cell lines from different tissues and in primary lung tumors and metastatic melanomas.