Correction: several of the proteins that I thought were "fibrous" are actually "filamentous." For example, while axons and dendrites are "hairlike" in structure, I don't know that any of the proteins they contain are fibrous proteins. They do contain filamentous proteins, but these are probably globular proteins, rather than fibrous proteins. Examples of fibrous proteins include keratins, collagens and elastins. Actin, myosin and tubulin are filamentous proteins.