Background: Successful embryo implantation requires the development of a receptive endometrium, involving substantial remodelling of cell surface glycoprotein network to convert the endometrium to an adhesive state. Dystroglycan (DG) is a large cell surface glycoprotein/adhesion molecule, consisting of α and β subunits which are derived from a single gene. While β-DG is anchored within the plasma membrane, α-DG attaches to β-DG extracellularly. The central region of α-DG is highly glycosylated and mediates adhesion. However, this region is masked by its large N-terminus (α-DG-N, 312 amino acid long). We hypothesized that α-DG-N on the plasma membrane is a barrier for embryo implantation and that endometrial receptivity requires α-DG-N removal by a protease, proprotein convertase 5/6 (PC6). In addition, α-DG-N that is removed from the membrane and presented in uterine fluid is a potential biomarker for receptivity. Aims: To prove that α-DG-N removal by PC6 is essential for endometrial receptivity and to establish an ELISA to quantify α-DG-N in uterine fluid. Methods and Results: We engineered two distinct DG constructs: wild type (WT) and mutant (Mut) in which the PC6-cleavage site was mutated. Ishikawa cells stably expressing these DG constructs were established and studied for their adhesiveness to fibronectin and trophoblast spheroids (surrogates for human embryos). Compared to cells expressing WT DG, cells expressing the Mut DG, which is resistant to PC6-cleavage resulting in α-DG-N contained on the plasma membrane, significantly reduced receptivity. We also established a specific ELISA to quantify α-DG-N in uterine lavages to detect receptivity. Conclusion: We demonstrated that DG plays an important role in endometrial receptivity, but α-DG-N removal by PC6 is essential. The α-DG-N removed from the membrane is a potential biomarker for receptivity.