Final answer:
Covalent bonds are principally involved in the tertiary and sometimes quaternary structures of proteins, helping to stabilize their three-dimensional conformation through interactions like disulfide linkages.
Step-by-step explanation:
Covalent bonds are indeed a type of interaction that can occur within the structure of proteins. Specifically, these interactions are predominantly involved in the tertiary structure of proteins, although they can also play a role in quaternary structures. Covalent bonds, such as disulfide linkages, occur between cysteine amino acids when their side chains are brought into proximity as the protein folds. This covalent bonding helps to stabilize the protein's three-dimensional structure and is essential for its proper function.
In addition to covalent bonds, other interactions such as hydrophobic interactions, ionic bonding, hydrogen bonding, and van der Waals forces also contribute significantly to the tertiary structure of proteins. While primary structure is defined by the sequence of amino acids connected by peptide bonds, which are also covalent in nature, the context of this question appears to target the higher-order structural interactions.