Identification and ultrastructural localization of a calretinin-like calcium-binding protein (protein 10) in the guinea pig and rat inner ear

Dechesne, Claude J.; Winsky, Lois; Kim, Hong N.; Goping, G.; Vu, Thuc D.; Wenthold, Robert J.; Jacobowitz, David M.

doi:10.1016/0006-8993(91)91224-o

Cited by 103 publications

(58 citation statements)

References 24 publications

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“…Sound-dependent bending of these bundles opens up potassium and calcium ion channels resulting in the propagation of nerve impulses to the brain (43). It has recently been demonstrated that high concentrations of calcium-binding proteins parvalbumin (44) and calbindin (45), approaching 300 M and 970 M respectively, are found in the stereocilia along with significant concentrations of two other calcium-binding proteins (calretinin (46,47), and oncomodulin (48 -50)). Additionally, stereocilia have the Ca 2ϩ ATPase pump PMAC2 at a concentration of ϳ2000 molecules/m 2 on the plasma membrane (51).…”

Section: Possible Allosteric Interactions Involving the N-terminal DImentioning

confidence: 99%

Ion-dependent Polymerization Differences between Mammalian β- and γ-Nonmuscle Actin Isoforms

Bergeron

Zhu

Thiem

et al. 2010

Journal of Biological Chemistry

106

123

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␤-and ␥-nonmuscle actins differ by 4 amino acids at or near the N terminus and distant from polymerization interfaces. ␤-Actin contains an Asp 1 -Asp 2 -Asp 3 and Val 10 whereas ␥-actin has a Glu 1 -Glu 2 -Glu 3 and Ile 10 . Despite these small changes, conserved across mammals, fish, and birds, their differential localization in the same cell suggests they may play different roles reflecting differences in their biochemical properties. To test this hypothesis, we established a baculovirus-driven expression system for producing these actins in isoform-pure populations although contaminated with 20 -25% insect actin. Surprisingly, Ca-␥-actin exhibits a slower monomeric nucleotide exchange rate, a much longer nucleation phase, and a somewhat slower elongation rate than ␤-actin. In the Mg-form, this difference between the two is much smaller. Ca-␥-actin depolymerizes half as fast as does ␤-actin. Mixing experiments with Caactins reveal the two will readily co-polymerize. In the Ca-form, phosphate release from polymerizing ␤-actin occurs much more rapidly and extensively than polymerization, whereas phosphate release lags behind polymerization with ␥-actin. Phosphate release during treadmilling is twice as fast with ␤-as with ␥-actin. With Mg-actin in the initial stages, phosphate release for both actins correlates much more closely with polymerization. Calcium bound in the high affinity binding site of ␥-actin may cause a selective energy barrier relative to ␤-actin that retards the equilibration between G-and F-monomer conformations resulting in a slower polymerizing actin with greater filament stability. This difference may be particularly important in sites such as the ␥-actin-rich cochlear hair cell stereocilium where local mM calcium concentrations may exist.

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Section: Possible Allosteric Interactions Involving the N-terminal DImentioning

confidence: 99%

Ion-dependent Polymerization Differences between Mammalian β- and γ-Nonmuscle Actin Isoforms

Bergeron

Zhu

Thiem

et al. 2010

Journal of Biological Chemistry

106

123

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“…In mammalian vestibular organs, narrow hair cells with smalldiameter hair bundles are considered immature type II hair cells and are characterized by immunoreactivity for the calciumbinding protein calretinin (Dechesne et al, 1991(Dechesne et al, , 1994; a subset of bullfrog saccular hair cells similarly shows high calretinin levels (Edmonds et al, 2000). In whole-mount saccules, NHE6 colocalized with calretinin immunoreactivity (Fig.…”

Section: Nhe6 and Nhe9 Are Expressed In Hair Bundlesmentioning

confidence: 99%

Vestibular Hair Bundles Control pH with (Na⁺, K⁺)/H⁺Exchangers NHE6 and NHE9

Hill¹,

Brett²,

Chyou³

et al. 2006

J. Neurosci.

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In hair cells of the inner ear, robust /Hϩ exchange, which we propose is performed by NHE9 in hair bundles, exploits the high-K ϩ endolymph, responds only to pH imbalance across the bundle membrane, is unaffected by the ϩ80 mV endocochlear potential, and uses mechanisms already present in the ear for K ϩ recycling. This mechanism allows the hair cell to remove H ϩ generated by Ca 2ϩ pumping without ATP hydrolysis in the cell.

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“…Although many vestibular hair bundles were labeled intensely with antibodies against PMCA2, a subset of bundles had lower levels of this isozyme. These bundles usually belonged to hair cells that were immunoreactive for the calcium-binding protein calretinin; consistent with their generally smaller bundles, these cells may be immature type II hair cells (Dechesne et al, 1991(Dechesne et al, , 1994. Basolateral membranes of utricular hair cells were labeled with antibodies against PMCA1 and PMCA3.…”

Section: Pmca Isoforms In Rat Organ Of Corti and Utriculusmentioning

confidence: 99%

Plasma Membrane Ca²⁺-ATPase Isoform 2a Is the PMCA of Hair Bundles

et al. 2001

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Mechanoelectrical transduction channels of hair cells allow for the entry of appreciable amounts of Ca2+, which regulates adaptation and triggers the mechanical activity of hair bundles. Most Ca2+that enters transduction channels is extruded by the plasma membrane Ca2+-ATPase (PMCA), a Ca2+pump that is highly concentrated in hair bundles and may be essential for normal hair cell function. Because PMCA isozymes and splice forms are regulated differentially and have distinct biochemical properties, we determined the identity of hair bundle PMCA in frog and rat hair cells. By screening a bullfrog saccular cDNA library, we identified abundant PMCA1b and PMCA2a clones as well as rare PMCA2b and PMCA2c clones. Using immunocytochemistry and immunoprecipitation experiments, we showed in bullfrog sacculus that PMCA1b is the major isozyme of hair cell and supporting cell basolateral membranes and that PMCA2a is the only PMCA present in hair bundles. This complete segregation of PMCA1 and PMCA2 isozymes holds for rat auditory and vestibular hair cells; PMCA2a is the only PMCA isoform in hair bundles of outer hair cells and vestibular hair cells and is the predominant PMCA of hair bundles of inner hair cells. Our data suggest that hair cells control plasma membrane Ca2+-pumping activity by targeting specific PMCA isozymes to distinct subcellular locations. Because PMCA2a is the only Ca2+pump present at appreciable levels in hair bundles, the biochemical properties of this pump must account fully for the physiological features of transmembrane Ca2+pumping in bundles.

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Identification and ultrastructural localization of a calretinin-like calcium-binding protein (protein 10) in the guinea pig and rat inner ear

Cited by 103 publications

References 24 publications

Ion-dependent Polymerization Differences between Mammalian β- and γ-Nonmuscle Actin Isoforms

Ion-dependent Polymerization Differences between Mammalian β- and γ-Nonmuscle Actin Isoforms

Vestibular Hair Bundles Control pH with (Na⁺, K⁺)/H⁺Exchangers NHE6 and NHE9

Plasma Membrane Ca²⁺-ATPase Isoform 2a Is the PMCA of Hair Bundles

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Identification and ultrastructural localization of a calretinin-like calcium-binding protein (protein 10) in the guinea pig and rat inner ear

Cited by 103 publications

References 24 publications

Ion-dependent Polymerization Differences between Mammalian β- and γ-Nonmuscle Actin Isoforms

Ion-dependent Polymerization Differences between Mammalian β- and γ-Nonmuscle Actin Isoforms

Vestibular Hair Bundles Control pH with (Na+, K+)/H+Exchangers NHE6 and NHE9

Plasma Membrane Ca2+-ATPase Isoform 2a Is the PMCA of Hair Bundles

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Vestibular Hair Bundles Control pH with (Na⁺, K⁺)/H⁺Exchangers NHE6 and NHE9

Plasma Membrane Ca²⁺-ATPase Isoform 2a Is the PMCA of Hair Bundles