Muscle Biochemistry

Question 1

What is the arrangement of the proteins of the myofilament?

Answer 1

Each actin filaments is surrounded by 3 myosin filaments

Each myosin filament is surrounded by 6 actin filaments

Question 2

What is the biochemical basis of muscle activity?

Answer 2

Both actin and myosin possess ATPase activity
Accessory proteins are alpha actinins, capZ, tropomyosin and troponin
Alpha actinin is a an actin binding protein comprising spectrin and dystrophin
CapZ located in the Z band, stabilizes and protects the assembly of actin filaments
Titin or connectin- largest known protein

Question 3

What are the characteristics of myosin and actin?

Answer 3

Myosin has 2 heavy chain and a 2 pairs of light chains
Actin is made of G and f actin
Tropomyosin covers the myosin binding sites of actin
Troponin is heterodimeric:TnC, TnI and TnT

Question 4

What is the dystrophin-glycoprotein complex?

Answer 4

Multi subunit complex
Dystrophin is a major intracellular protein , defect causes DMD., links complex with actin
DMD inherited X linked manner(X-linked recessive)