G B Witman — Page 5 | PubMed Health

PubMed1971

Comparison of the microtubule proteins of neuroblastoma cells, brain, and Chlamydomonas flagella.

Intact A microtubules isolated from outer doublet microtubules of Chlamydomonas flagella contain two separable proteins (tubulins) that differ in molecular weight and in amino-acid composition. The microtubule protein isolated from brain or neuroblastoma cells also has two electrophoretically distinct tubulins. Although the two tubulins of brain and neuroblastoma cells are electrophoretically similar to each other, only one of these tubulins migrates with the flagellar tubulins. This is the first evidence that (a) isolated, morphologically intact, single microtubules from flagella contain at least two different tubulins, and (b) at least one of these tubulins differs from tubulins that are isolated from other sources.

Animals↗

PubMedDate not supplied

Isolated flagellar outer arm dynein translocates brain microtubules in vitro.

The inner and outer arms of the flagellar axoneme generate the forces needed for flagellar movement; these arms contain ATPases called dyneins. To date, there has been no method for studying the mechanochemical transducing activity of isolated dyneins. Recently, it was found that the brain microtubule-associated protein (MAP) 1C is a microtubule-activated ATPase with the structural and force-producing properties of dynein. MAP 1C translocates microtubules in an in vitro gliding assay, suggesting that such an assay could also be used with axonemal dyneins. Here, we demonstrate that outer-arm dynein isolated from sea urchin (Strongylocentrotus purpuratus) sperm and adsorbed to a glass coverslip can translocate calf-brain microtubules along the surface of the coverslip. Our results conclusively demonstrate that outer-arm dynein by itself is capable of generating shearing forces. The ability to examine the force-generating properties of flagellar dynein in vitro should greatly facilitate studies of the mechanism of action of this important mechanochemical transducer.

Adenosine Triphosphatases↗