ch369_f09_class7

ch369_f09_class7 - CytoskeletalProteinsandMotorProteins...

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“Cytoskeletal Proteins and Motor Proteins” (Chapter 5 of textbook) Cells contain a “ cytoskeleton ”, formed by fibrous  proteins. Cytoskeleton gives a cell shape, and helps keeps  things organized.
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We have recently talked about some “ globular  proteins ” such as myoglobin and hemoglobin. ext:  Describe some  “ Fibrous proteins ”. These globular proteins are roughly spherical  in shape, have mostly hydrophobic amino acids  on the inside, hydrophilic a.a. on the outside. Fibrous proteins of the cytoskeleton:      . Also, other fibrous proteins that are exterior to cells:                 collagen, keratin .
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The cytoskeleton in a typical eukaryotic cell  contains several types of fibers: Microfilaments  (thin, about 70 Å diameter) Intermediate filaments  (a bit thicker, 100 Å) Microtubules  (thicker, about 240 Å diameter) These act as tracks for “motor proteins” which  use chemical energy (energy from converting ATP  to ADP) to move molecules.
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The green thing is ATP  bound to the actin. Actin has about 375  a.a. (medium sized  protein). First describe  microfilaments . Microfilaments are made of a protein called  actin .
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Actin can exist as a  globular protein  (G-actin), and can  also assemble into microfilaments (F-actin). Microfilaments are dynamic: They constantly shrink and  grow by adding or losing actin monomers from their ends. Microfilaments usually grow faster at their “+ end”.
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Microfilament length can be controlled by  capping  proteins . Microfilaments can be broken down by “ severing  proteins ”.
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+ energy Hydrolysis of ATP releases  energy ; formation of ATP  consumes energy. ATP ADP energ y P i + +
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Newly formed actin filaments have bound ATP. Actin hydrolyzes the ATP to ADP, causing conformational  change. Microtubule-binding proteins can distinguish newly 
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This note was uploaded on 01/21/2010 for the course CH 369 taught by Professor Kbrowning during the Fall '07 term at University of Texas.

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ch369_f09_class7 - CytoskeletalProteinsandMotorProteins...

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