title: Kinesin walks the line: single motors observed by atomic force microscopy.
abstract: Motor proteins of the kinesin family move actively along microtubules to transport cargo within cells. How exactly a single motor proceeds on the 13 narrow lanes or protofilaments of a microtubule has not been visualized directly, and there persists controversy on the relative position of the two kinesin heads in different nucleotide states. We have succeeded in imaging Kinesin-1 dimers immobilized on microtubules with single-head resolution by atomic force microscopy. Moreover, we could catch glimpses of single Kinesin-1 dimers in their motion along microtubules with nanometer resolution. We find in our experiments that frequently both heads of one dimer are microtubule-bound at submicromolar ATP concentrations. Furthermore, we could unambiguously resolve that both heads bind to the same protofilament, instead of straddling two, and remain on this track during processive movement.
authors.affiliation: Department of Physics and Astronomy, Vrije Universiteit Amsterdam, de Boelelaan, Amsterdam, The Netherlands.
authors.forename: Iwan A T
authors.initials: IA
authors.lastname: Schaap
authors.forename: Carolina
authors.initials: C
authors.lastname: Carrasco
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: de Pablo
authors.forename: Christoph F
authors.initials: CF
authors.lastname: Schmidt
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D003198:Computer Simulation; D006801:Humans; D055767:Immobilized Proteins / Q000378:metabolism; D016547:Kinesins / Q000737:chemistry / Q000378:metabolism*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D009492:Neurospora crassa / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D055503:Protein Multimerization / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects
chemical_list: D055767:Immobilized Proteins; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate; D016547:Kinesins