Proteins also are involved in giving certain cells mobility. For example, sperm cells have a structure known as a Flagellum. And that flagellum is necessary to allow the sperm cell to actually move and navigate through the vaginal cavity and through the oviduct, the fallopian tube, in the female reproductive system. And this Flagellum is composed predominantly of different types of proteins. Now, proteins are also involved in protecting our cells in our body from different types of pathogenic agents. So antibodies and antigens consist of proteins.