Aaron Lockhart

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Kinesin and ncd motor proteins are homologous in sequence yet move in opposite directions along microtubules. We have previously shown that monomeric kinesin and ncd bind in the same orientation on equivalent sites relative to the ends of tubulin sheets of known polarity. We now report cryoelectron microscope images of 16-protofilament microtubules(More)
The kinesin molecular motor "walks" processively along microtubules, touching down with alternate motor domains and transiently bridging between sites spaced 8 nm apart axially. To allow bridging, the coiled coil tail of kinesin would need to unzip a region immediately adjacent to the heads, and the tail region sequence at this point indeed contains(More)
Kinesin superfamily molecular motors step along microtubules (MTs) via a cycle of conformational changes which is coupled to ATP turnover. To probe the coupling mechanism, we titrated the effects of various nucleotides on MT binding by two superfamily members; MT plus-end-directed kinesin and MT minus-end-directed non claret disjunctional (ncd). For both(More)
Kinesin is a 'motor' molecule, consisting of two head domains, an alpha-helical coiled coil rod, and a tail part that binds to its cargo. When expressed in a bacterial system, the head domain is functional, and can bind to microtubules with the stoichiometry of one head per tubulin dimer. Kinesin moves along microtubules by means of a cyclic process of(More)
We have investigated the kinetic properties of the slow plus end directed microtubule (MT) motor Eg5. The recombinantly expressed fusion protein E437GST, containing residues 12-437 of Eg5 fused to the N-terminus of glutathione S-transferase (GST), is dimeric and motile, translocating MTs at an average speed of 0.063 (+/-0.01) micrometers(-1). The kinetics(More)
The effect of hematocrit on pressure-flow relations for the pulmonary circulation was studied by means of an isolated lung preparation. Lobes taken from mongrel dogs were perfused with autologous blood of hematocrits ranging from 23 to 75. The apparatus was of a closed circuit type, consisting of the lobe being perfused by means of a roller pump so that a(More)
To ascertain the relationship between the physical properties of polymer supports and the observed response of luminescence-based oxygen sensors, a quenching-based method was developed to measure oxygen diffusion in polymers. The method offers advantages over existing quenching-based techniques since it allows a simple correction for films of high optical(More)
The head or motor domain of the ncd (non-claret disjunctional) molecular motor is 41% identical to that of kinesin, yet moves along microtubules in the opposite direction to kinesin. We show here that despite the reversed directionality of ncd, its kinetics in solution are homologous in key respects to those of kinesin. The rate limiting step, ADP release,(More)
To investigate the orientation of alpha- and beta-tubulin heterodimers within microtubules, we cloned a phage display antibody to alpha-tubulin. The N-terminal 100 residues of alpha-tubulin were bacterially expressed and used to select clones from a large repertoire of antibody-expressing phagemid particles. One clone reacted with the expressed(More)