Identity and Origin of the ATPase activity associated with neuronal microtubules. I. The ATPase activity is associated with membrane vesicles.

Abstract

Microtubule protein purified from brain tissue by cycles of in vitro assemblydisassembly contains ATPase activity that has l~een postulated to be associated with microtubule-associated proteins (MAPs) and therefore significant for studies of microtubule-dependent motility. In this paper we demonstrate that >90% of the ATPase activity is particulate in nature and may be derived from contaminating membrane vesicles. We also show that the MAPs (MAP-l, MAP-2, and tau factors) and other high molecular weight polypeptides do not contain significant amounts of ATPase activity. These findings do not support the concept of "brain dynein" or of MAPs with ATPase activity.

Stable complexes of axoplasmic vesicles and microtubules: protein composition and ATPase activity.

“…The actual amount is probably even less than this since the Mg ++ ATPase activity of the MtVC is not inhibited by either oligomycin or sodium azide (NAN3). Also, the MtVC ATPase activity does not have the characteristics of the F~-like enzyme identified in vesicles which eopurify with brain microtubules (Murphy et al, 1983).…”

A microtubule-activated ATPase from sea urchin eggs, distinct from cytoplasmic dynein and kinesin.

“…Other ATPases present in microtubule preparations have been described (23)(24)(25)(26)(27)(28)(29). None has pharmacological properties comparable to our activity, and the activity of these species was unaffected by microtubules.…”

Identification of a novel force-generating protein, kinesin, involved in microtubule-based motility

“…However, it is not known which proteins comprise the translocator. Dynein is the only molecule known to interact with microtubules to generate motive force (Gibbons, 1981), but attempts to identify dynein in neural tissue, where organelle movements are common, have been unsuccessful (Murphy et al, 1983).…”