Important Features of the Cytoskeleton
  
 Fiber Type Short Hand 

 Subunit

 Shape Size (nm) Motor Molecules Polarity?
     Protein Shape        
 microtubules MT  tubulin globular  hollow  25  dynein 
(+ --> -)
 yes
kinesin
(- --> +)
 microfilaments MF  actin   globular solid  5-9  myosin  yes 

 intermediate 
filaments

IF   >5 kinds ##   fiber solid?
**
 8-12  ----  no
 Fiber 
Important Drugs
Temporary Structures  Permanent
Structures
Accessory Proteins 
Depolymerize  Stabilize
 MT colchicine  taxol  spindle fibers   cilia, 
flagella
MAPs = microtubule associated proteins *
MF cytochalasins phalloidin cleavage 
furrow
muscle 
(thin filaments)
ABPs = actin binding proteins* 
 
 *   See Chapter 15 of Becker for more details on MAPs & ABPs--  for reference purposes only.
** IF = cable of solid fibers; cable may be hollow.
## Cytoplasmic subunits are tissue specific. For types of IF's, see Becker Table 15-4 (15-3).