Abstract: A human prourokinase-like polypeptide having the following amino acid sequence:(Met).Ser.sup.1 -X.sup.156.Y.sup.157.Z.sup.158 --wherein Met is an occasionally present methionine, Ser is the first N-terminal serine, X is the 156th arginine or other amino acid, Y is the 157th proline, glycine, alanine or valine, Z is the 158th lysine or arginine, and the solid lines represent the same amino acid sequences as corresponding parts of an amino acid sequence of a natural type human prourokinase or a human prourokinase-like polypeptide wherein the 135th lysine is changed to an amino acid other than a basic amino acid, or substantially the same amino acid sequence as the above-mentioned amino acid sequence, is provided.Moreover, a DNA segment coding for the above-mentioned polypeptide; a plasmid containing the DNA segment; E. coli transformed with the plasmid; a process for production of the polypeptide characterized by culturing the E.