A functionally unglycosylated transmembrane protein having a molecular weightof about 24kd which is ubiquitous in human cells and exhibits the same speciesspecificity as hepatitis C virus. The protein is capable of binding to HCVsurface proteins and is a putative HCV cellular receptor. As such it has manyapplications in the fields of diagnosis and treatment of HCV infection and inthe design of HCV therapeutics.