Final answer:
The myofilaments of skeletal muscles are composed of the contractile proteins myosin and actin. Thick filaments consist of myosin, while thin filaments are mainly composed of actin; these proteins interact during muscle contractions.
Step-by-step explanation:
The two contractile proteins that make up the myofilaments of skeletal muscles are myosin and actin. Myofibrils are the key contractile elements within muscle tissue and are composed of smaller structures known as myofilaments, which come in two main types: thick and thin filaments. Thick filaments mainly consist of the protein myosin, known for its role in muscle contraction by interacting with actin.
On the other hand, thin filaments are primarily composed of the protein actin, which has specific binding sites for myosin. The interaction between these two proteins is responsible for muscle contractions, assisted by regulatory proteins such as troponin and tropomyosin, which regulate the attachment of myosin to actin.