Patent ID: 7867973

Claim:
A follistatin variant polypeptide, which (a) comprises any one domain structure selected from FSI-FSI, FSI-FSI-FSIII, FSN-FSI-FSI, and FSN-FSI-FSI-FSIII, wherein FSI denotes follistatin domain I comprising SEQ ID NO: 1 or amino acids 95-164of SEQ ID NO: 4, FSIII denotes follistatin domain III comprising amino acids 245-316 of SEQ ID NO: 4, and FSN denotes an N-terminal domain comprising amino acids 1-94 of SEQ ID NO: 4, and the domains are each linked directly or via a linker polypeptide, wherein the linker polypeptide contains no cysteines and the length of the linker polypeptide is 1-10 amino acids; (b) does not comprise an amino acid sequence that is represented by formula (I): Cys-(X 1 ) a -Cys-(X 2 ) b -Cys-(X 3 ) c -Cys-(X 4 ) d -Cys-(X 5 ) e -Cys-(X 6 ) f -Cys-(X 7 ) g -Cys-(X 8 ) h -Cys-(X 9 ) i -Cys (SEQ ID NO: 30) wherein X 1 , X 2 , X 3 , X 4 , X 5 , X 6 , X 7 , X 8 , and X 9 each independently represents the same or a different naturally occurring amino acid residue other than cysteine, “a” represents an integer between 2 and 6, “b” represents an integer between 3 and 7, “c” represents an integer between 7 and 11, “d” represents an integer between 0 and 4, “e” represents an integer between 1and 6, “f” and “g” represent integers between 8 and 12, “h” represents an integer between 4 and 8, and “i” represents an integer between 11 and 15 and has 50% or more homology with the amino acid sequence of SEQ ID NO: 2 or SEQ ID NO: 29; and (c) selectively inhibits GDF-8 activity as compared with its inhibition of activin activity.