title: Prestin surface expression and activity are augmented by interaction with MAP1S, a microtubule-associated protein.
abstract: Prestin is a member of the SLC26 family of anion transporters that is responsible for outer hair cell (OHC) electromotility. Measures of voltage-evoked charge density (Q(sp)) of prestin indicated that the protein is highly expressed in OHCs, with single cells expressing up to 10 million molecules within the lateral membrane. In contrast, charge density measures in transfected cells indicated that they express, at best, only a fifth as many proteins on their surface. We sought to determine whether associations with other OHC-specific proteins could account for this difference. Using a yeast two-hybrid technique, we found microtubule-associated protein 1S (MAP1S) bound to prestin. The interaction was limited to the STAS domain of prestin and the region connecting the heavy and light chain of MAP1S. Using reciprocal immunoprecipitation and Forster resonance energy transfer, we confirmed these interactions. Furthermore, co-expression of prestin with MAP1S resulted in a 2.7-fold increase in Q(sp) in single cells that was paralleled by a 2.8-fold increase in protein surface expression, indicating that the interactions are physiological. Quantitative PCR data showed gradients in the expression of prestin and MAP1S across the tonotopic axis that may partially contribute to a previously observed 6-fold increase in Q(sp) in high frequency hair cells. These data highlight the importance of protein partner effects on prestin.
authors.affiliation: Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.
authors.forename: Jun-Ping
authors.initials: JP
authors.lastname: Bai
authors.forename: Alexei
authors.initials: A
authors.lastname: Surguchev
authors.forename: Yudelca
authors.initials: Y
authors.lastname: Ogando
authors.forename: Lei
authors.initials: L
authors.lastname: Song
authors.forename: Shumin
authors.initials: S
authors.lastname: Bian
authors.forename: Joseph
authors.initials: J
authors.lastname: Santos-Sacchi
authors.forename: Dhasakumar
authors.initials: D
authors.lastname: Navaratnam
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics* / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D003051:Cochlea / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D003078:Colchicine / Q000494:pharmacology; D017931:DNA Primers; D031541:Fluorescence Resonance Energy Transfer; D005849:Gerbillinae; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009928:Organ Specificity; D009925:Organ of Corti / Q000502:physiology; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D000076988:Sulfate Transporters
chemical_list: D027321:Anion Transport Proteins; D017931:DNA Primers; D008869:Microtubule-Associated Proteins; C498722:Pres protein, Cavia porcellus; D011506:Proteins; C409207:Slc26a5 protein, rat; D000076988:Sulfate Transporters; D003078:Colchicine