PHR1, an integral membrane protein of the inner ear sensory cells, directly interacts with myosin 1c and myosin VIIa.

Raphael Etournay (1) , Aziz El-Amraoui (1) , Amel Bahloul (1) , Stéphane Blanchard (1) , Isabelle Roux (1) , Guillaume Pézeron (1) , Nicolas Michalski (1) , Laurent Daviet (2) , Jean-Pierre Hardelin (1) , Pierre Legrain (3) , Christine Petit (1, 4)

1 Génétique des Déficits Sensoriels
2 Hybrigenics [Paris]
3 SHFJ - Service Hospitalier Frédéric Joliot
4 Collège de France - Chaire Génétique et physiologie cellulaire

By using the yeast two-hybrid technique, we identified a candidate protein ligand of the myosin 1c tail, PHR1, and found that this protein can also bind to the myosin VIIa tail. PHR1 is an integral membrane protein that contains a pleckstrin homology (PH) domain. Myosin 1c and myosin VIIa are two unconventional myosins present in the inner ear sensory cells. We showed that PHR1 immunoprecipitates with either myosin tail by using protein extracts from cotransfected HEK293 cells. In vitro binding assays confirmed that PHR1 directly interacts with these two myosins. In both cases the binding involves the PH domain. In vitro interactions between PHR1 and the myosin tails were not affected by the presence or absence of Ca2+ and calmodulin. Finally, we found that PHR1 is able to dimerise. As PHR1 is expressed in the vestibular and cochlear sensory cells, its direct interactions with the myosin 1c and VIIa tails are likely to play a role in anchoring the actin cytoskeleton to the plasma membrane of these cells. Moreover, as both myosins have been implicated in the mechanotransduction slow adaptation process that takes place in the hair bundles, we propose that PHR1 is also involved in this process.

Mots clés: Myosin VIIa; Myosin 1c; PHR1; Inner ear; Hair cell

Domaines: Sciences du Vivant [q-bio]; Biochimie, Biologie Moléculaire

Raphael Etournay, Aziz El-Amraoui, Amel Bahloul, Stéphane Blanchard, Isabelle Roux, et al.. PHR1, an integral membrane protein of the inner ear sensory cells, directly interacts with myosin 1c and myosin VIIa.. Journal of Cell Science, 2005, 118 (13), pp.2891-99. ⟨10.1242/jcs.02424⟩. ⟨pasteur-01541848⟩