Regulatory Proteins,
Intrasarcomeric Proteins,
Intersarcomeric Proteins, and
Additional Muscle Fibers
Leslie Garcia
September 4, 2008
Animal Growth and Development
Tropomyosin
• Tropomyosin is an actin-binding protein that
regulates actin mechanics
F- Actin Groove
•Is a filamentous proteins that are the
main constituent of the thin filaments of
muscle fibers.
F- Actin
Troponin
• Interaction between the proteins is key to
regulation of cross-bridge development during
muscle contraction.
• Interaction between troponin, F-actin,
tropomyosin, and the thin filament is key
to regulation of cross-bridge
development during muscle contraction.
Intrasarcomeric
Proteins
Intrasarcomeric Proteins
• Are located in the myofibril
• Help maintain and organize structure
Definition:
• Proteins within the sarcomere
Titin or Connectin
• Titin or Connectin helps maintain the
structure of a half sarcomere.
• Responsible for the resting tension of a
muscle.
Nebulin
• Nebulin is to maintain muscle structure
• Can provide a template for building and
maintaining filamentous actin.
Intersarcomeric
Proteins
Intersarcomeric Proteins
• Align the cylindrical myofibrils in a
muscle fiber
Definition:
• proteins positioned outside the myofibril
Desmin
• Responsible for “tying” the myofibrils
together.
Definition:
• Encircles the myofibrils at the Z-line and
radiates out perpendicular to the long
axis of the myofibril.
Additional Components of
Muscle Fibers
• Nuclei Muscle: contain multinucleated
cells
• Mitochondria: are oblong cellular
organelles that are responsible for
generating energy substrates for the cell.
• Sarcoplasm: is the cellular cytoplasm of a
muscle cell