BIOL273 Chapter Notes - Chapter 3: Myosin Light-Chain Kinase, Endoplasmic Reticulum, Skeletal Muscle
11 Sep 2016
School
Department
Course
Professor
Document Summary
When calcium binds to troponin in skeletal muscle, it causes tropomyosin to unto be removed from myosin binding sites on actin, allowing myosin to bind to actin. But with calmodulin, when it binds to calcium, this activates myosin light chain kinase (mlck). Mlck then activates myosin light chains by phosphorylating them, increasing myosin atpase activity. Then myosin is able to form cross bridges and slides along actin to create muscle tension. To relax, calcium is pumped back out of the cell or back into sarcoplasmic reticulum. This causes calmodulin to unbind from calcium, mlck activity decreases and then myosin light chains on heads are dephosphorylated by myosin phosphotase, decreasing myosin atpase activity. Located in heart muscle (skeletal attached to bones, smooth- forms walls of hollow organs/tubes) Has t tubules (larger than skeletal and branch inside myocardial cells) and sarcoplasmic reticulum like skeletal, smooth only has sarcoplasmic ret.
