The present invention relates to a two-step method for isolating proteins
from the cystine-knot superfamily based on dye ligand affinity
chromatography and reversed-phase chromatography. Advantageously, the
method can be performed in a relatively short period of time, involves
inexpensive reagents, and requires little sample preparation before and
during the purification process. Protein fusions between cystine-knot
proteins and proteins of interest are further provided for the isolation
of said protein of interest or complexes containing said protein of
interest using the two-step method disclosed.