Direct observation of processive movement by individual myosin V molecules.
Myosin V is an unconventional myosin thought to move processively along actin filaments. To have hard evidence for the high processivity, we sought to observe directly the movement by individual native chick brain myosin V (BMV) molecules with fluorescent calmodulin. Single BMV molecules did exhibit highly processive movement along actin filaments fixed to a coverslip. BMV continued to move up to the barbed end of its actin track, and did not readily detach from action. The barbed end, therefore, got brighter with time, because of a constant stream of BMV traffic. The maximum speed of the processive movement was 1 microm/s, and the maximum actin-activated ATPase rate was 2.4 s(-1). These values apparently imply that BMV travels a great distance, 400 nm, per an ATPase cycle.
Sakamoto
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T
Department of Physics, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa-ken, 920-1192, Japan.
Amitani
I
I
Yokota
E
E
Ando
T
T
D000199:Actins / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001921:Brain; D002147:Calmodulin / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002232:Carbocyanines / Q000378:metabolism; D002645:Chickens; D004789:Enzyme Activation / Q000187:drug effects; D005456:Fluorescent Dyes / Q000378:metabolism; D007700:Kinetics; D018715:Microscopy, Video; D020409:Molecular Motor Proteins / Q000378:metabolism; D009068:Movement / Q000187:drug effects; D024701:Myosin Type V; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009994:Osmolar Concentration; D011189:Potassium Chloride / Q000494:pharmacology; D011485:Protein Binding; D011489:Protein Denaturation
D000199:Actins; D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D002232:Carbocyanines; D005456:Fluorescent Dyes; D020409:Molecular Motor Proteins; D009419:Nerve Tissue Proteins; C078829:chicken brain myosin-V p190; C089187:cyanine dye 3; D011189:Potassium Chloride; D000251:Adenosine Triphosphatases; D024701:Myosin Type V