The present invention is based on the seminal discovery that hedgehog proteins undergo autoproteolytic cleavage which results in two separate proteins having distinct functional and structural characteristics. The two polypeptides, referred to as the "N" and "C" fragments of hedgehog, or N-terminal and C-terminal fragments, respectively, are produced after specific cleavage at a G.sup..dwnarw. CF site recognized by the autoproteolytic domain in the native protein. The "C" fragment functions as a cholesterol transferase during autoproteolysis thus allowing cholesterol modification of the "N" fragment. Thus, in one embodiment, the invention provides a substantially pure polypeptide characterized by having an amino acid sequence derived from amino terminal amino acids of a hedgehog protein and having at its carboxy terminus, a G.dwnarw.CF cleavage site specifically recognized by a proteolytic activity of the carboxy terminal fragment of the native hedgehog polypeptide. The invention also provides a substantially pure polypeptide characterized by having an amino acid sequence of a hedgehog polypeptide or a fragment derived from amino terminal amino acids of a hedgehog polypeptide, wherein the polypeptide or fragment thereof comprises a sterol moiety. Fragments derived from a native hedgehog polypeptide are included and preferably include extracellular amino acid residues, such as those derived from the N fragment. In one embodiment of the invention, the sterol moiety is cholesterol.
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