Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1989-3-28
pubmed:abstractText
Intestinal epithelia have a brush border membrane of numerous microvilli each comprised of a cross-linked core bundle of 15-20 actin filaments attached to the surrounding membrane by lateral cross-bridges; the cross-bridges are tilted with respect to the core bundle. Isolated microvillar cores contain actin (42 kD) and three other major proteins: fimbrin (68 kD), villin (95 kD), and the 110K-calmodulin complex. The addition of ATP to detergent-treated isolated microvillar cores has previously been shown to result in loss of the lateral cross-bridges and a corresponding decrease in the amount of the 110-kD polypeptide and calmodulin associated with the core bundle. This provided the first evidence to suggest that these lateral cross-bridges to the membrane are comprised at least in part by a 110-kD polypeptide complexed with calmodulin. We now demonstrate that purified 110K-calmodulin complex can be readded to ATP-treated, stripped microvillar cores. The resulting bundles display the same helical and periodic arrangement of lateral bridges as is found in vivo. In reconstitution experiments, actin filaments incubated in EGTA with purified fimbrin and villin form smooth-sided bundles containing an apparently random number of filaments. Upon addition of 110K-calmodulin complex, the bundles, as viewed by electron microscopy of negatively stained images, display along their entire length helically arranged projections with the same 33-nm repeat of the lateral cross-bridges found on microvilli in vivo; these bridges likewise tilt relative to the bundle. Thus, reconstitution of actin filaments with fimbrin, villin, and the 110K-calmodulin complex results in structures remarkably similar to native microvillar cores. These data provide direct proof that the 110K-calmodulin is the cross-bridge protein and indicate that actin filaments bundled by fimbrin and villin are of uniform polarity and lie in register. The arrangement of the cross-bridge arms on the bundle is determined by the structure of the core filaments as fixed by fimbrin and villin; a contribution from the membrane is not required.
pubmed:grant
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-11894965, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-1202021, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-14473959, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-2956266, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-2956267, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-2961614, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-2963011, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-3157690, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-4253329, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-4254541, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-4944636, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-5432063, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-568557, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-569662, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-574874, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6094541, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6177699, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6311843, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6367959, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6682042, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6823301, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6893051, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6893424, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6893667, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6893989, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6894925, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6935660, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6947259, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-6998986, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-7200986, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-7430135, http://linkedlifedata.com/resource/pubmed/commentcorrection/2918023-942051
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0021-9525
pubmed:author
pubmed:issnType
Print
pubmed:volume
108
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
495-502
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Reassociation of microvillar core proteins: making a microvillar core in vitro.
pubmed:affiliation
Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.