The 37-kDa/67-kDa laminin receptor acts as the cell-surface receptor for the cellular prion protein

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Abstract
Recently, we identified the 37‐kDa laminin receptor precursor (LRP) as an interactor for the prion protein (PrP). Here, we show the presence of the 37‐kDa LRP and its mature 67‐kDa form termed high‐affinity laminin receptor (LR) in plasma membrane fractions of N2a cells, whereas only the 37‐kDa LRP was detected in baby hamster kidney (BHK) cells. PrP co‐localizes with LRP/LR on the surface of N2a cells and Semliki Forest virus (SFV) RNA transfected BHK cells. Cell‐binding assays reveal the LRP/LR‐dependent binding of cellular PrP by neuronal and non‐neuronal cells. Hyperexpression of LRP on the surface of BHK cells results in the binding of exogenous PrP. Cell binding is similar in PrP+/+ and PrP0/0 primary neurons, demonstrating that PrP does not act as a co‐receptor of LRP/LR. LRP/LR‐dependent internalization of PrP is blocked at 4°C. Secretion of an LRP mutant lacking the transmembrane domain (aa 86–101) from BHK cells abolishes PrP binding and internalization. Our results show that LRP/LR acts as the receptor for cellular PrP on the surface of mammalian cells.