Abstract

The plasma membrane of mammalian cochlear outer hair cells contains prestin, a unique motor protein. Prestin is the fifth member of the solute carrier protein 26A family. Orthologs of prestin are also found in the ear of non-mammalian vertebrates such as zebrafish and chicken. However, these orthologs are electrogenic anion exchangers/transporters with no motor function. Amphibian and reptilian lineages represent phylogenic branches in the evolution of tetrapods and subsequent amniotes. Comparison of the peptide sequences and functional properties of these prestin orthologs offer new insights into prestin evolution. With the recent availability of the lizard and frog genome sequences, we examined amino acid sequence and function of lizard and frog prestins to determine how they are functionally and structurally different from prestins of mammals and other non-mammals. Somatic motility, voltage-dependent nonlinear capacitance (NLC), the two hallmarks of prestin function, and transport capability were measured in transfected human embryonic kidney cells using voltage-clamp and radioisotope techniques. We demonstrated that while the transport capability of lizard and frog prestin was compatible to that of chicken prestin, the NLC of lizard prestin was more robust than that of chicken’s and was close to that of platypus. However, unlike platypus prestin which has acquired motor capability, lizard or frog prestin did not demonstrate motor capability. Lizard and frog prestins do not possess the same 11-amino-acid motif that is likely the structural adaptation for motor function in mammals. Thus, lizard and frog prestins appear to be functionally more advanced than that of chicken prestin, although motor capability is not yet acquired.

Highlights

  • Prestin, found in the membrane of mammalian cochlear outer hair cells (OHCs), is a unique voltage-dependent motor protein that does not depend on ATP and calcium [1,2,3]

  • It is suggested that the evolution of mammalian prestin motor function occurred as a result of multiple episodic adaptive events [40]

  • We evaluated the characteristics of lPres and fPres for anion transport, nonlinear capacitance (NLC) and motor capability

Read more

Summary

Introduction

Found in the membrane of mammalian cochlear outer hair cells (OHCs), is a unique voltage-dependent motor protein that does not depend on ATP and calcium [1,2,3]. Amino acid sequence analyses have indentified prestin to be the fifth member of a distinct anion transporter family called solute carrier protein 26A, or SLC26A [2]. Individual members of this eleven-member family [6] serve two distinct functions. While most members are anion transporter/exchangers, prestin is the only member that functions as a molecular motor with piezoelectric capability on a microsecond time scale [3,7]. The anion transport and motor capabilities of prestin are independent [10]

Objectives
Methods
Results
Conclusion
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.