JCB logo
PeproTech: Your source for Cell Biology Research Reagents
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
This Article
Right arrow PDF (Full Text)
Right arrow Alert me when this article is cited
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Burton, P. R.
Right arrow Articles by Himes, R. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Burton, P. R.
Right arrow Articles by Himes, R. H.
Right arrowPubmed/NCBI databases
*Compound via MeSH
*Substance via MeSH
Hazardous Substances DB
*DIMETHYL SULFOXIDE
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

The Journal of Cell Biology, Vol 77, 120-133, Copyright © 1978 by The Rockefeller University Press

ARTICLES

Electron microscope studies of pH effects on assembly of tubulin free of associated proteins. Delineation of substructure by tannic acid staining

PR Burton and RH Himes

Bovine brain tubulin, purified by phosphocellulose chromatography (PC), was assembled in the presence of 10% dimethyl sulfoxide (DMSO), and the reaction was monitored turbidimetrically. Samples were fixed in glutaraldehyde-tannic acid after completion of polymerization, as indicated by no further change in absorbance, and then sectioned and studied electron microscopy, with special attention being given to the arrangement of protofilaments in the walls of formed elements. Samples of PC-tubulin were polymerized in buffer having various pH values from 6.0 to 7.7. At the lower pH values, only branched and flattened ribbons of protofilaments are formed. At intermediate values, the ribbons are unbranched, narrower, and more curved in cross section; complete microtubules are also seen. At the higher pH values, the predominate formed elements are complete microtubules. Most of the complete microtubules examined in this study had 14 wall protofilaments. The effect of pH on tubulin assembly was shown not to be an effect of DMSO. The dimers of associated protofilaments in ribbons and microtubules are conceptually viewed as having trapezoidal profiles in cross section, and, as additional dimers are added, the "C"-shaped ribbon closes to form a tube. The tilt angle of the lateral surfaces of the "trapezoidal" dimers will determine the number of wall protofilaments in the microtubules. At low pH, it is theorized that the trapezoidal profile of the dimer is shifted to a more rectangular configuration such that flat ribbons are formed by the lateral association of dimers. Also, variously shaped ribbon structures are formed at intermediate pH values, including "S"- and "W"-shaped structures, and elements shaped like a figure "6," all representing ribbons viewed in cross section. By visualizing the trapezoidal dimer in three-dimensions, and by arbitrarily indexing its six binding surfaces, it is possible to discuss interdimer binding in terms of preferred and possible binding interactions.
Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents