Interaction of brain mitochondria with microtubules reconstituted from brain tubulin and MAP2 or TAU.
To explore the behaviour of microtubule-associated proteins, MAP2 and TAU in the interactions of mitochondria with microtubules, an homologous acellular system has been reconstituted with organelles isolated from rat brain. We have established a quantitative in vitro binding assay based on the cosedimentation of 125I-labeled microtubules with mitochondria. We found that binding of microtubules to mitochondria was concentration dependent and saturable. Binding was insensitive to ATP. A comparison of taxol-stabilized microtubules prepared from MAP-free tubulin or tubulin coated with TAU or MAP2 showed that the microtubule-associated proteins diminished, or reduced to background levels, the formation of complexes with mitochondria. In contrast, the amount of MAP-free taxol microtubules that cosedimented with mitochondria increased two- and six-fold when mitochondria were coated with MAP2 or TAU. These studies suggest that the two major brain MAPs could have a crosslinking or a spacing role, depending on their organelle localization.
Jung
D
D
INSERM Unité 338, Biologie de la Communication Cellulaire, Strasbourg, France.
Filliol
D
D
Miehe
M
M
Rendon
A
A
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002474:Cell-Free System; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014404:Tubulin / Q000302:isolation & purification / Q000378:metabolism*; D016875:tau Proteins / Q000378:metabolism*
D008869:Microtubule-Associated Proteins; D014404:Tubulin; D016875:tau Proteins; D000255:Adenosine Triphosphate; D017239:Paclitaxel