COLL 37 |
| Marcel E. Janson1, Jacob W. J. Kerssemakers2, Mathilde E. de Dood2, and Marileen Dogterom2. (1) Dept. of Cell & Developmental Biology, University of Pennsylvania, 421 Curie Blvd, 1037 BRB II/III, Philadelphia, PA 19104, (2) FOM Institute for Atomic and Molecular Physics (AMOLF), Kruislaan 407, Amsterdam, 1098 SJ, Netherlands |
| Microtubules are long filamentous protein structures that randomly alternate between periods of elongation and shortening in a process that involves GTP hydrolysis. In living cells, this ability to switch is important during processes such as chromosomal and nuclear positioning. During these processes polymerizing microtubules generate pushing forces in close contact with various cellular structures. Studies of polymerization under load are therefore needed to fully understand microtubule dynamics in cells. In our in vitro experimental setup microtubules were made to grow against micro-walls and polymerization forces were determined from the observed buckling. Length changes could be measured with a precision of 10 nm. Growth velocity decreased and microtubules switched more frequently to shortening at increasing force. The observed dependencies strongly suggest that the rate of subunit addition is affected by force in a way consistent with a Brownian ratchet mechanism, whereas the rates of GTP hydrolysis and subunit removal remain unchanged. |
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Bio-Colloids
2:00 PM-4:30 PM, Sunday, March 28, 2004 Marriott -- Grand Ballroom J, Oral
Division of Colloid and Surface Chemistry |