Provided herein are fusion proteins comprising a first polypeptide and a second polypeptide, wherein the second polypeptide has phase behavior. The first polypeptide may be a polypeptide having a desirable biological activity, such as a polypeptide with therapeutic, cosmetic, and/or industrial importance. Fusing the first polypeptide to the polypeptide with phase behavior facilitates purification thereof, and may also help to stabilize the first polypeptide during expression, storage, or after exposure to various conditions known to unfold, degrade, or misfold proteins.