Well everything is made of complex proteins. There isn't one single organism just comprised of proteins. For example keratin is a protein that is made when RNA passes through a ribosome. Now this protein may be used in different functions, one is to strengthen hair/nails. To simplify: anything living that is eukaryotic. (multi_cellular organisms bigger than bacteria and viruses.)
The answer is hox gene.
Hox genes are responsible for an embryo's body plan. They determine different body structures - legs, vertebrae, antennae, wings, depending on groups. Mutation in hox genes is serious mutation since it affects the early stages of embryo and consequently, normal development. If a mutation occurs in the hox gene for legs growth, the legs will not develop.
Explanation:
because the tilt of the earth on its axis
