On macrotubule structure

Warfield, R. K. N.; Bouck, G. Benjamin

doi:10.1016/0022-2836(75)90365-4

Cited by 10 publications

(1 citation statement)

References 14 publications

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“…3B), the protofilaments of the macrotubules were coiled at a -36°angle to the long axis of the macrotubule . The number of protofilament pairs that assembled to form a macrotubule was calculated as a function of the macrotubule diameter, the protofilament angle to the long axis, and the protofilament pair width (65). In vitro assembled macrotubules were cold labile, such that the birefringent highly refractile bundles disappeared within 60 s when 10 t1 of the preparation on a microscope slide was cooled to 4°C .…”

Section: In Vitro Assembly Of Macrotubules From Surf Clam Tubulinmentioning

confidence: 99%

Purification and characterization of oocyte cytoplasmic tubulin and meiotic spindle tubulin of the surf clam Spisula solidissima.

Suprenant¹,

Rebhun²

1984

The Journal of Cell Biology

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Assembly-competent tubulin was purified from the cytoplasm of unfertilized and parthogenetically activated oocytes, and from isolated meiotic spindles of the surf clam, Spisula solidissima . At 22°C or 37°C, Spisula tubulin assembled into 48-51-nm macrotubules during the first cycle of polymerization and 25-nm microtubules during the third and subsequent cycles of assembly . Macrotubules were formed from sheets of 26-27 protofilaments helically arranged at a 36°angle relative to the long axis of the polymer and were composed of a and a tubulins and several other proteins ranging in molecular weight from 30,000 to 270,000 . Third cycle microtubules contained 14-15 protofilaments in cross-section and were composed of >95% a and ,Q tubulins . After three cycles of polymerization at 37°C, unfertilized and activated oocyte tubulin self-assembled into microtubules at a critical concentration (Ccr) of 0.09 mg/ml. At the physiological temperature of 22°C, unfertilized oocyte tubulin assembled into microtubules at a Ccr of 0.36 mg/ml, activated oocyte tubulin assembled at a Ccr of 0.42 mg/ml, and isolated meiotic spindle tubulin assembled at a Ccr of 0.33 mg/ml . The isoelectric points of tubulin from both unfertilized oocytes and isolated meiotic spindles were 5 .8 for a tubulin and 5.6 for # tubulin . In addition, one dimensional peptide maps of oocyte and spindle a and ,Q tubulins were very similar, if not identical . These results indicate that unfertilized oocyte tubulin and tubulin isolated from the first meiotic spindle are indistinguishable on the basis of assembly properties, isoelectric focusing, and one dimensional peptide mapping . These results suggest that the transition of tubulin from the quiescent oocyte state to that competent to form spindle microtubules in vivo does not require special modification of tubulin but may involve changes in the availability of microtubule organizing centers or assembly-promoting microtubule-associated proteins .In 1972, Weisenberg (68, 69) described a particulate and sedimentable pool of tubulin that was assayed indirectly by colchicine binding in homogenates of unfertilized surf clam oocytes. The sedimentable tubulin was present in unfertilized oocytes in a granular and filamentous matrix suggested to be a storage form of tubulin. The level of sedimentable tubulin decreased to a minimum level at 5 min after parthenogenetic activation (time of nuclear envelope breakdown) and rose to a maximum value at meiotic metaphase. In addition to sedimentable tubulin, Burnside et al. (10) and Rosenfeld (70) showed that homogenates of activated Spisula solidissima oocytes at 28°C would assemble into microtubules, forming aster-like structures associated with centrioles . No microtubule assembly or aster formation was observed when homogenates of unfertilized oocytes were warmed, although a crude preparation of organizing centers from activated oocytes induced aster formation in homogenates of unactivated oocytes. Unfortunately, the complexity of the fractions used did not all...

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Section: In Vitro Assembly Of Macrotubules From Surf Clam Tubulinmentioning

confidence: 99%