|
rdf:type |
|
|
lifeskim:mentions |
|
|
pubmed:issue |
4
|
|
pubmed:dateCreated |
1996-10-17
|
|
pubmed:abstractText |
Evidence that 13 or 14 contiguous tubulin-GTP subunits are sufficient to cap and stabilize a microtubule end and that loss of only one of these subunits results in the transition to rapid disassembly(catastrophe) was obtained using the slowly hydrolyzable GTP analogue guanylyl-(a,b)-methylene-diphosphonate (GMPCPP). The minus end of microtubules assembled with GTP was transiently stabilized against dilution-induced disassembly by reaction with tubulin-GMPCPP subunits for a time sufficient to cap the end with an average 40 subunits. The minimum size of a tubulin-GMPCPP cap sufficient to prevent disassembly was estimated from an observed 25- to 2000-s lifetime of the GMPCPP-stabilized microtubules following dilution with buffer and from the time required for loss of a single tubulin-GMPCPP subunit from the microtubule end (found to be 15 s). Rather than assuming that the 25- to 2000-s dispersion in cap lifetime results from an unlikely 80-fold range in the number of tubulin-GMPCpP subunits added in the 25-s incubation, it is proposed that this results because the minimum stable cap contains 13 to 14 tubulin-GMPCPP subunits. As a consequence, a microtubule capped with 13-14 tubulin-GMPCPP subunits switches to disassembly after only one dissociation event (in about 15 s), whereas the time required for catastrophe of a microtubule with only six times as many subunits (84 subunits) corresponds to 71 dissociation events (84-13). The minimum size of a tubulin-GMPCPP cap sufficient to prevent disassembly was also estimated with microtubules in which a GMPCPP-cap was formed by allowing chance to result in the accumulation of multiple contiguous tubulin-GMPCPP subunits at the end, during the disassembly of microtubules containing both GDP and GMPCPP. Our observation that the disassembly rate was inhibited in proportion to the 13-14th power of the fraction of subunits containing GMPCPP again suggests that a minimum cap contains 13-14 tubulin-GMPCPP subunits. A remeasurement of the rate constant for dissociation of a tubulin-GMPCPP subunit from the plus-end of GMPCPP microtubules, now found to be 0.118 s-1, has allowed a better estimate of the standard free energy for hydrolysis of GMPCPP in a microtubule and release of Pi: this is +0.7 kcal/mol, rather than -0.9 kcal/mol, as previously reported.
|
|
pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1003481,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1057175,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1387400,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1421571,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1421572,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1447301,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1525467,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1558755,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-1671762,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-2004433,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-2050742,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-2160472,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-2351702,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-2379239,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-2397205,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-2405278,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-2513874,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-3170635,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-3392017,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-6504138,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-7495804,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-7704569,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-7962059,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-8218889,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-8299144,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-8485321,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730106-8590813
|
|
pubmed:language |
eng
|
|
pubmed:journal |
|
|
pubmed:citationSubset |
IM
|
|
pubmed:chemical |
|
|
pubmed:status |
MEDLINE
|
|
pubmed:month |
Apr
|
|
pubmed:issn |
1059-1524
|
|
pubmed:author |
|
|
pubmed:issnType |
Print
|
|
pubmed:volume |
7
|
|
pubmed:owner |
NLM
|
|
pubmed:authorsComplete |
Y
|
|
pubmed:pagination |
663-75
|
|
pubmed:dateRevised |
2009-11-18
|
|
pubmed:meshHeading |
|
|
pubmed:year |
1996
|
|
pubmed:articleTitle |
Evidence that a single monolayer tubulin-GTP cap is both necessary and sufficient to stabilize microtubules.
|
|
pubmed:affiliation |
Department of Biochemistry, University of North Carolina, Chapel Hill 27599-7260, USA.
|
|
pubmed:publicationType |
Journal Article
|
