Identification of a 120 kd hair-bundle myosin located near stereociliary tips

Neuron. 1993 Oct;11(4):581-94. doi: 10.1016/0896-6273(93)90071-x.


By adapting to sustained stimuli, hair cells of the internal ear maintain their optimal sensitivity to minute displacements. Biophysical experiments have suggested that adaptation is mediated by a molecular motor, most likely a member of the myosin family. To provide direct evidence for the presence of myosin isozymes in hair bundles, we used photoaffinity labeling with vanadate-trapped uridine and adenine nucleotides to identify proteins of 120, 160, and 230 kd in a preparation of hair bundles purified from the bullfrog's sacculus. The photoaffinity labeling properties of these proteins, particularly the 120 kd protein, resembled those of other well-characterized myosins. A 120 kd hair-bundle protein was also recognized by a monoclonal antibody directed against a vertebrate myosin I isozyme. Immunofluorescence microscopy localized this protein near the beveled top edge of the hair bundle, the site of mechanoelectrical transduction and adaptation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Antibodies, Monoclonal
  • Autoradiography
  • Calcium / pharmacology
  • Cilia / chemistry*
  • Cilia / enzymology
  • Electrophoresis, Polyacrylamide Gel
  • Fluorescent Antibody Technique
  • Hair Cells, Auditory / chemistry*
  • Hair Cells, Auditory / enzymology
  • Isoenzymes / analysis
  • Isoenzymes / isolation & purification
  • Molecular Weight
  • Myosins / analysis
  • Myosins / isolation & purification*
  • Phosphorus Radioisotopes
  • Rana catesbeiana
  • Uridine Triphosphate / metabolism
  • Vanadates / pharmacology


  • Antibodies, Monoclonal
  • Isoenzymes
  • Phosphorus Radioisotopes
  • Vanadates
  • Adenosine Triphosphate
  • Myosins
  • Calcium
  • Uridine Triphosphate