The Mitotic Apparatus

Kane, Robert E.

doi:10.1083/jcb.25.1.137

Cited by 110 publications

(33 citation statements)

References 12 publications

(20 reference statements)

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“…A totally different procedure for the preparation of 22S protein, not involving organic solvents, may shed some light on the question. Mazia et al (1961 b) have shown spindle isolates to be stabilized by the presence of dithiodiglycol, while Kane ( a, 1965 has demonstrated that many glycols not containing the disulfide linkage serve the same purpose. However, the dithiodiglycol isolates are generally more Where molecular weight determinations were carried out, the molecular weight is indicated in terms of multiples of "n," the average weight of the smallest subunit thus far obtained (1 l~,000).…”

Section: Discussion the 2 2 S Particlementioning

confidence: 99%

“…difficult to dissolve in neutral salt than their hexylene glycol counterparts and both become insoluble on standing (Dirksen, 1964;Kane and Forer, 1965), requiring the use of either high pH or sulfhydryl reagents for solubilization. In this study, the 22S protein, even in high salt, will form aggregates when either sulfhydryl or disulfide compounds are present.…”

Section: Discussion the 2 2 S Particlementioning

confidence: 99%

“…The 21-22S particle, seen as a component common to both dissolved asters (Dirksen, 1964) and spindles (Kane, 1965(Kane, b, 1967Sakai, 1966), appears to be a likely candidate for such a protein, particularly in view of its predominance in hexylene glycol isolates solubilized at neutrality where the least amount of denaturation or dissociation would be expected to OCCUr. The purpose of this study is twofold: first, to characterize the 22S protein obtainable from hexylene glycol mitotic apparatus isolates and whole egg lysates (Kane, 1965(Kane, b, 1967 or acetone powder extracts of unfertilized eggs (Kane and Hersh, 1959) and, second, to investigate subunit association in order to gain some insight into the quaternary structure of the 22S particle and attempt to correlate the resulting subunit data with the results of previous investigations. Implicit in such a study, of course, is proof that the 22S fraction of the mitotic apparatus is identical with that of the whole egg.…”

Section: Introductionmentioning

confidence: 99%

“…However, Miki-Noumura (1965) obtained directly a 2.3S material from alkalinedissolved microfilaments of hexylene glycol mitotic apparatus isolates. Recently, Kane (1965Kane ( b, 1967 has observed one major 22S particle and a minor 4-5S heterogeneous component from hexylene glycol mitotic apparatus isolates dissolved in high salt at neutral pH.…”

Section: Introductionmentioning

confidence: 99%

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The Mitotic Apparatus

Stephens

1967

The Journal of Cell Biology

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The major 22S protein of the hexylene glycol-isolated mitotic apparatus has been characterized fi'om spindle isolates and extracts of whole eggs and acetone powders of eggs from the sea urchins Strongylocentrotus purpuratus, Strongylocentrotus droebachiensis, and Arbacia punctulata.The protein is free of nucleotide, lipid, and ATPase activity. Essentially identical in amino acid composition, proteins from these species show a relatively high content of glutamic and aspartic acids and are fairly rich in hydrophobic amino acids. Optical rotatory dispersion studies indicate a helical content of about 20%, a value consistent with the proline content of the protein. The purified proteins have sedimentation rates in the range of 22-24S, diffusion constants of 2.4-2.5F, intrinsic viscosities of 3.7-4.3 ml/g, a partial specific volume of 0.74, and an average molecular weight of 880,000. Electron microscopy indicates a globular molecule with dimensions of approximately 150 by 200 A; such size and symmetry are consistent with hydrodynamic measurements. The 22S protein yields 6-7S, 9-10S, and 13-14S subunits below pH 4 or above pH 11. The 13-14S component has an estimated molecular weight of 600,000-700,000. A 5-6S particle is formed in 8 M urea or 5 M guanidine hydrochloride, while at pH 12 the 6-7S subunit is seen; each particle has a molecular weight of 230,000-240,000. In 8 M urea plus 2% mercaptoethanol or at pH 13, the molecular weight becomes 105,000-120,000; under these conditions the particle sediments at 2.5-3S and 4S, respectively. On the basis of these molecular weights, the 6-7S, 9--10S, 13-14S, and the parent 22S particle should be dimer, tetramer, hexamer, and octamer, respectively, of the 105,000-120,000 molecular weight subunit. The various subunits will reform the 22S particle when returned to neutral buffer, with the exception of the mercaptoethanol-treated urea subunit where breakage of disulfide bonds results in a polydisperse aggregate. The 22S particle itself is not susceptible to sulfhydryl reagents, implying either that the disulfide bonds are inaccessible or that they are unnecessary for maintenance of tertiary structure once the 22S particle has formed from subunits.

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Section: Discussion the 2 2 S Particlementioning

confidence: 99%

Section: Discussion the 2 2 S Particlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Mitotic Apparatus

Stephens

1967

The Journal of Cell Biology

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“…12). Several other proteins (19) and protein structures (20,21) also show increased stability in glycols.…”

Section: Concentrcflion Of Kci (M)mentioning

confidence: 99%

A Melting Point for the Birefringent Component of Muscle

Aronson

1966

The Journal of Cell Biology

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The A filament of the striated muscle sarcomere is an ordered aggregate of one or a few species of proteins. Ordering of these filaments into a parallel array is the basis of birefringence in the A region, and loss of birefringence is therefore a measure of decreased order. Heating caused a large decrease in the birefringence of glycerinated rabbit psoas muscle fibers over a narrow temperature range (∼3°C) and a large decrease in both the birefringence and optical density of the A region of Drosophila melanogaster fibrils. These changes were interpreted as a loss of A filament structure and were used to define a transition temperature (Ttr) as a measure of the stability of the A region. Since the transition temperature was sensitive to pH, ionic strength, and urea, solvent conditions which often affect protein structure, it is an experimentally useful indicator for factors affecting the structure of the A filament. Fibers from glycerinated frog muscle were less stable over a wide pH range than fibers from glycerinated rabbit muscle, a fact which demonstrates a species difference in structure. Glycerinated rabbit fibrils heated to 70°C shortened to about 40% of their initial length. The extent of shortening was not correlated with the loss of birefringence, and phase-contrast microscopy showed that this shortening occurred in the I region as well as in the A region. This response may be useful for studying the I filament and actin in much the same way that the decrease in birefringence was used for studying the A filament and myosin. The observations presented show that some properties of muscle proteins can be studied essentially in situ without the necessity of first dispersing the structure in solutions of high or low ionic strength.

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Foamed Plastics

Suh

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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This article is concerned with the general theory of expansion, manufacturing processes, properties, and applications of foamed (cellular) plastics. The high strength‐to‐weight ratio, excellent insulating properties, and cushioning properties of cellular plastics have contributed to the development and growth of the broad range of cellular plastics in use. The total usage of foamed plastics in the United States has risen from 441 thousand metric tons in 1967 to 1.6 million metric tons in 1982 and has been projected to rise to about 2.8 million metric tons in 1995. The manufacturing processes for cellular polymers are described in terms of three classified methods based on the cell growth and stabilization processes. The properties of cellular plastics including mechanical, thermal, electrical, and environmental aging properties, are summarized. A general discussion is given on the properties of cellular plastic necessary in many applications such as the comfort cushioning, thermal insulation, packaging, structural components, buoyancy, electrical insulation, and space‐filling markets. A brief discussion is also given on the process economics, raw materials, and energy considerations for the commercial products of primary importance.

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The Mitotic Apparatus

Cited by 110 publications

References 12 publications

The Mitotic Apparatus

The Mitotic Apparatus

A Melting Point for the Birefringent Component of Muscle

Foamed Plastics

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