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Cell Biology International (2012) 36, 16 (Printed in Great Britain)
Bidirectional transport of organelles: unity and struggle of opposing motors
Sofiya A. Bryantseva and Olga N. Zhapparova1
A N Belozersky Institute of PhysicoChemical Biology of Lomonosov Moscow State University, Vorobjevy Gory, 1, Moscow 119991, Russia
Bidirectional transport along microtubules is ensured by opposing motor proteins: cytoplasmic dynein that drives cargo to the minus-ends and various kinesins that generally move to the plus-ends of microtubules. Regulation of motor proteins that are simultaneously bound to the same organelle is required to maintain directional transport and prevent pausing of cargo pulled away by motors of opposite polarity. Debates of the recent decade have been focused on two possible mechanisms of such regulation: (i) coordination, which implies that only one type of motors is active at a given time, and (ii) tug-of-war, which assumes that both motors are active at the same time and that direction of transport depends on the outcome of motor's confrontation. The initial idea of coordination has been challenged by observations of simultaneous activity of plus- and minus-end-directed motors applied to the same cargo. Analysis of the available data indicates that coordination and tug-of-war theories rather complement than contradict each other: cargo interacts with two teams of active motors, the resulting direction and the winner team are determined by coordination complexes, but the activity of the loser team is never completely inhibited and remains at some background level. Such persisting activity might enhance the overall efficiency of transport by increasing processivity or helping to overcome the obstacles on microtubule track.
Key words: bidirectional transport, dynactin, dynein, huntingdin, kinesin, tug-of-war
Abbreviations: GFP, green fluorescent protein, HAP1, huntingtin-associated protein 1, LSD2, least significant difference 2
1To whom correspondence should be addressed (email firstname.lastname@example.org).
Received 5 August 2011; accepted 12 September 2011
Published as Cell Biology International Immediate Publication 15 September 2011, doi:10.1042/CBI20110413
© The Author(s) Journal compilation © 2012 Portland Press Limited