KP222 Lecture Notes - Lecture 9: Myocyte, T-Tubule, Conformational Change
Lecture 9:
Thin Myofilaments
Ca is a sensor
Tropomyosin: protein that regulates actin and myosin interactions
Thick Myofilaments
Two heads: actin binding site, and a ATP site (hydrolyze)
Center has no myosin heads: M line
The Sliding Filament Theory
Each muscle cell has many myofibrils running together in parallel and every myofibril
has many sarcomeres in series (line up end to end)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Tropomyosin: protein that regulates actin and myosin interactions. Two heads: actin binding site, and a atp site (hydrolyze) Each muscle cell has many myofibrils running together in parallel and every myofibril has many sarcomeres in series (line up end to end) Sacrolemma travels down the t tubule, ca travel and is released. Ca bind to the troponin (thin filament) moves tropomyosin binding of actin and myosin. All need electrical signal to have calcium release. Release of ca2+ in response to membrane depolarization. Tnc = calcium receptor: signals tropomyosin to roll off of myosin binding sites on actin. If calcium isn"t there then tropomyosin will block the sites. Biggest role for calcium would be 1 because without ca2+ the cycle wont happen. That a sarcomere is the functional unit of a muscle fibre. How these proteins slide past one another during the cross-bridge cycle to shorten the sarcomere and contract the muscle fibre.
