1 / 19

Molecular Motors

Molecular Motors. Lecture 33 ` BSCI 420/421 Nov 18, 2002 “To survive the 21 st century, our thinking must be creative and humane as well as analytical.” - Robert Kuhn Myosins Kinesins Dyneins. Myosins Are a family of motor proteins that bind to & move along actin

chase
Download Presentation

Molecular Motors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Molecular Motors • Lecture 33 ` BSCI 420/421 Nov 18, 2002 • “To survive the 21st century, our thinking must be • creative and humane as well as analytical.” • - Robert Kuhn • Myosins • Kinesins • Dyneins

  2. Myosins • Are a family of motor proteins that bind to & move along actin • filaments toward the + ends. • Large globular heads bind and split ATP • Undergo a configurational change that changes the angle • of the head with respect to an a-helical tail. E.g. Myosin II

  3. Myosin II of vertebrate muscle

  4. The Myosin family portrait N--------------------------------C

  5. In vitro motility assay: Evidence of myosin’s motor activity (Fig. 53) (wrong way)

  6. X-ray crystal structures of myosin & kinesin heads

  7. Myosin cross-bridge cycle

  8. Skeletal Muscle fibers are multinucleate muscle cells formed by fusion of myoblasts. (fig 68)

  9. Sarcomere structure of myofibrils, dark=A band, light=I band

  10. X-sec of myofibril, insect flight muscle, verts slightly different. (Fig.70)

  11. Sliding filament model (Fig.71) a-actinin

  12. MT-based Motors: Kinesin & Dynein Kinesin is a large protein with 4 polypeptide chains Like myosin it has 2 heavy chains, each w a globular head domain and long a-helical tail. 2 light chains on cargo- MT binding end binding (vary in diff. cells w diff. cargo) ATP-binding site Coiled-coil in each head tail

  13. Kinesins + KIFs - (Kinesin Family + members + Freeze- Etched, Shadowed TEM + 2 HC in tail

  14. Comparison of kinesin and myosin mechanochemical cycles

  15. 3. Dyneins are a family of minus end directed MT motors. Largest and fastest molecular motors (14 mm/sec vs 2 mm/sec for kinesin)(fig 56)

  16. Dynein moves vesicles and the Golgi app toward the cell center. • Untreated B) Nocodazole • Fig. 62

More Related