MAP 1C is a microtubule-activated ATPase which translocates microtubules in vitro and has dynein-like properties.

Abstract

Abstract. We observe that one of the high molecular mass microtubule-associated proteins (MAPs) from brain exhibits nucleotide-dependent binding to microtubules. We identify the protein as MAP 1C, which was previously described in this laboratory as a minor component of standard microtubule preparations (Bloom, G. S., T. Schoenfeld, and R. B. Vallee, 1984, J. Cell Biol., 98:320-330). We find that MAP 1C is enriched in microtubules prepared in the absence of nucleotide. Kinesin is also found in these preparations, but can be specifically extracted with GTP. A fraction highly enriched in MAP 1C can be prepared by subsequent extraction of the microtubules with ATE Two activities cofractionate with MAP 1C upon further purification, a microtubule-activated ATPase activity and a microtubule-translocating activity. These activities indicate a role for the protein in cytoplasmic motility. MAP 1C coelectrophoreses with the beta heavy chain of Chlamydomonas flagellar dynein, and has a sedimentation coefficient of 20S. Exposure to ultraviolet light in the presence of vanadate and ATP results in the production of two large fragments of MAP 1C. These characteristics suggest that MAP 1C may be a cytoplasmic analogue of axonemal dynein.

Laser-transected microtubules exhibit individuality of regrowth, however most free new ends of the microtubules are stable.

“…Second, the observed time course of replacement of laser-dissociated MTs in the transected zone is much too slow to be explained by the active sliding of MTs. As our data showed, it took about 30 min to completely refill the 10-gm-wide transected zone with MTs; but, the reported rate of active sliding of MTs of the same polarity ranges from 0.2-16 gm/s -~ (21,29,32,33,35,43). Apparently, the expected time course of refill of the MT-depleted zone by some form of active sliding of the MTs would be much faster than the observed time course, even when the lowest reported rate of MT sliding is considered.…”

Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa

“…a, 1994 ;McKerracher & Heath, 1987 ;Heath, 1994). The discovery of microtubule-associated motor proteins (Hirokawa, 1982 ;Paschal et al, 1987) has helped us understand how organelles move inside the cell. Cytoplasmic dyneins and members of the kinesin superfamily are the main motor enzymes involved in vesicle translocation along microtubules (Haimo & Thaler, 1994 ;Hirokawa, 1998).…”

“…There is now growing evidence that both kinesins and cytoplasmic dyneins are involved in the traffic of secretory vesicles in fungal hyphae (Seiler et al, 1997 ;Wu et al, 1998 ;Inoue et al, 1998). Cytoplasmic dyneins are multisubunit enzymes involved in transport of membranous organelles towards the minus end of microtubules (Paschal et al, 1987 ;Schroer & Sheetz, 1991 ;Hirokawa, 1998). Kinesins are motor proteins involved in membrane transport towards the plus end of the microtubules (Vale et al, 1985 ;Hirokawa, 1982 ;Steinberg & Schliwa, 1996).…”

In vivo analysis of MT‐based vesicle transport by confocal reflection microscopy

“…The remarkably great speed implies an involvement of the MT-based motor molecules, most likely the classical Kinesin-I and the cytoplasmic dynein for the plus-and the minus-end directed runs, respectively. Interestingly, the speed measured for both the plus (848 6 17 nm/s) and the minus end directed motions (975 6 25 nm/s) is as high as determined for the conventional kinesin (600-1800 nm/sec) [Vale et al, 1985;von Massow et al, 1989;Bohm et al, 1999] and cytoplasmic dynein (800-1250 nm/s) [Paschal et al, 1987;Toba et al, 2006] in vitro, and about twice as high as measured in early syncytial embryos during phase I (407 6 49 nm/s and 475 6 42 nm/s for plus and minus end, respectively) [Welte et al, 1998]. This suggests that the MT-based transport machinery during the stages of the fast ooplasmic streaming is, not surprisingly, in a fully activated state.…”