* Carbon (C)

* Hydrogen (H)

* Oxygen (O)

* Nitrogen (N)

These four atoms form the backbone of the amino acid molecules that link together to create proteins.

In addition to these four main atoms, proteins may also contain small amounts of other atoms, such as:

* Sulfur (S): Found in the amino acid cysteine and involved in disulfide bonds.

* Phosphorus (P): Found in some modified amino acids.

However, these additional atoms are not present in all proteins and are less common than the four primary atoms.