Abstract: The present invention provides a fusion protein comprising a therapeutic polypeptide fused to one or more flexible unstructured polypeptides and a trimeric scaffold protein. The flexible unstructured polypeptide sequence within the fusion protein is exhibited as one or more pCloud sequences derived from human fibrinogen alpha chain, and may be flanked by a proteinous connecting moiety of human origin. Also provided are pharmaceutical compositions comprising the fusion protein, nucleic acid molecules encoding the fusion protein, vectors containing the nucleic acids, host cells transformed with the vectors, and methods of making the fusion proteins of the invention, and use thereof.