Pendrin Function and Regulation in &lt;i&gt;Xenopus&lt;/i&gt; Oocytes

Reimold, Fabian R.; Heneghan, John F.; Stewart, Andrew K.; Zelikovic, Israel; Vandorpe, David H.; Shmukler, Boris E.; Alper, Seth L.

doi:10.1159/000335106

Cited by 29 publications

(33 citation statements)

References 71 publications

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“…SLC26A3 (DRA/CLD) is a well-characterized chloride/bicarbonate exchanger present in the apical membrane of intestinal enterocytes where it works in conjunction with the NHE3 Na ϩ /H ϩ exchanger to mediate electroneutral NaCl reabsorption by the intestine (10,33,51,55). In addition to bicarbonate and chloride, SLC26A4 (pendrin) can also transport iodide, which may play an important role in the thyroid (12,46,56,57). SLC26A5 (prestin) acts as a voltage-sensitive chloride sensor in the lateral membrane of the cochlear outer hair cell (70).…”

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N-glycosylation and topology of the human SLC26 family of anion transport membrane proteins

Xia

Reithmeier

2014

American Journal of Physiology-Cell Physiology

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Li J, Xia F, Reithmeier RA. N-glycosylation and topology of the human SLC26 family of anion transport membrane proteins. Am J Physiol Cell Physiol 306: C943-C960, 2014. First published March 19, 2014 doi:10.1152/ajpcell.00030.2014.-The human solute carrier (SLC26) family of anion transporters consists of 10 members (SLCA1-11, SLCA10 being a pseudogene) that encode membrane proteins containing ϳ12 transmembrane (TM) segments with putative N-glycosylation sites (-NXS/T-) in extracellular loops and a COOHterminal cytosolic STAS domain. All 10 members of the human SLC26 family, FLAG-tagged at the NH2 terminus, were transiently expressed in HEK-293 cells. While most proteins were observed to contain both high-mannose and complex oligosaccharides, SLC26A2 was mainly in the complex form, SLC26A4 in the high-mannose form, and SLC26A8 was not N-glycosylated. Mutation of the putative N-glycosylation sites showed that most members contain multiple N-glycosylation sites in the second extracytosolic (EC) loop, except SLC26A11, which was N-glycosylated in EC loop 4. Immunofluorescence staining of permeabilized cells localized the proteins to the plasma membrane and the endoplasmic reticulum, with SLC26A2 highly localized to the plasma membrane. N-glycosylation was not a necessary requirement for cell surface expression as the localization of nonglycosylated proteins was similar to their wild-type counterparts, although a lower level of cell-surface biotinylation was observed. No immunostaining of intact cells was observed for any SLC26 members, demonstrating that the NH2-terminal FLAG tag was located in the cytosol. Topological models of the SLC26 proteins that contain an even number of transmembrane segments with both the NH2 and COOH termini located in the cytosol and utilized N-glycosylation sites defining the positions of two EC loops are presented. anion transport; calnexin; congenital chloride-losing diarrhea; CLD; membrane glycoproteins; membrane protein topology; membrane protein trafficking; D-glycosylation; SLC26; solute carrier THE SLC26 FAMILY OF ANION transporters is found in all kingdoms of life indicating a fundamental importance of these membrane proteins in biology. The human SLC26 family (Table 1) of anion transporters consists of 10 members (SLC26A1-11, A10 being a pseudo gene) (18,36,62,63). The human SLC26 proteins contain ϳ750 residues but range in size from 606 residues (SLC26A11) to 970 residues (SLC26A8). The proteins all consist of two major domains: a NH 2 -terminal membrane domain with ϳ12 putative transmembrane (TM) segments and a COOH-terminal STAS (sulfate transporter antagonist of anti-sigma factor) domain located in the cytosol (53). Structures of the STAS domain of several bacterial members of the SLC26 family have been obtained (4, 54), as well as the structure of a modified version of the STAS domain of rat SLC26A5 protein (40). All of the core structures resemble the Bacillus anti-sigma factor antagonist SpoIIAA, a 110 amino acid phospho-protein with an alpha/beta topology consisting of ...

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confidence: 99%

N-glycosylation and topology of the human SLC26 family of anion transport membrane proteins

Xia

Reithmeier

2014

American Journal of Physiology-Cell Physiology

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“…Specifically, Reimold et al describe the function and regulation of pendrin in an heterologous overexpression system, with isotopic flux, electrophysiology, and protein localization methodologies. They confirm the electroneutrality and 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS)-insensitivity of the transporter, show its pH insensitivity and anion selectivity sequence, and identify residues important for activity and regulation [12]. Two original papers in this Special Issue are devoted to assessment of the functionality of wild-type pendrin and several of its allelic variants found in the Palestinian, Israeli and Spanish populations [17,18].…”

Section: Scientific Content Of the Meetingmentioning

confidence: 66%

“…The coupling ratio of the ion exchange was initially unclear; again, considering homology with other members of the same family, and owing to earlier reports, it was assumed that pendrin participated in electrogenic anion exchange [8]. Later, we and others showed that pendrin anion transport was indeed non rheogenic (electroneutral) [9][10][11][12].…”

Section: Scientific Content Of the Meetingmentioning

confidence: 99%

The ESF Meeting on „The Proteomics, Epigenetics and Pharmacogenetics of Pendrin“

Dossena

Nofziger

Läng

et al. 2011

Cell Physiol Biochem

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Human pendrin (SCL26A4, PDS) is a 780 amino acid integral membrane protein with transport function. It acts as an electroneutral, sodium-independent anion exchanger for a wide range of anions, such as iodide, chloride, formate, bicarbonate, hydroxide and thiocyanate. Pendrin expression was originally described in the thyroid gland, kidney and inner ear. Accordingly, pendrin mutations with reduction or loss of transport function result in thyroid and inner ear abnormalities, manifested as syndromic (Pendred syndrome) and non-syndromic hearing loss with an enlarged vestibular aqueduct (ns-EVA). Pendred syndrome, the most common form of syndromic deafness, is an autosomal recessive disease characterized by sensorineural deafness due to inner ear malformations and a partial iodide organification defect that may lead to thyroid goiter. Later, it became evident that not only pendrin loss of function, but also up-regulation could participate in the pathogenesis of human diseases. Indeed, despite the absence of kidney dysfunction in Pendred syndrome patients, evidence exists that pendrin also plays a crucial role in this organ, with a potential involvement in the pathogenesis of hypertension. In addition, recent data underscore the role of pendrin in exacerbations of respiratory distresses including bronchial asthma and chronic obstructive pulmonary disease (COPD). Pendrin expression in other organs such as mammary gland, testis, placenta, endometrium and liver point to new, underscored pendrin functions that deserve to be further investigated.

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“…7). However, the possible contribution of this STAS domain region to pendrin-mediated electroneutral anion exchange [36,37] remains to be determined.…”

Section: Resultsmentioning

confidence: 99%

Molecular Dynamics Simulations of the STAS Domains of Rat Prestin and Human Pendrin Reveal Conformational Motions in Conserved Flexible Regions

Sharma

Zelikovic²,

Alper

2014

Cell Physiol Biochem

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Background: Molecular dynamics (MD) simulations provide valuable information on the conformational changes that accompany time-dependent motions in proteins. The reported crystal structure of rat prestin (PDB 3LLO) is remarkable for an α1-α2 inter-helical angle that differs substantially from those observed in bacterial STAS domains of SulP anion transporters and anti-sigma factor antagonists. However, NMR data on the rat prestin STAS domain in solution suggests dynamic features at or near the α1-α2 helical region (Pasqualetto et al JMB, 2010). We therefore performed a 100 ns 300K MD simulation study comparing the STAS domains of rat prestin and (modeled) human pendrin, to explore possible conformational flexibility in the region of the α1 and α2 helices. Methods: The conformation of the loop missing in the crystal structure of rat prestin STAS (11 amino acids between helix α1 and strand β3) was built using Modeller. MD simulations were performed with GROMACSv4.6 using GROMOS96 53a6 all-atom force field. Results: A subset of secondary structured elements of the STAS domains exhibits significant conformational changes during the simulation time course. The conformationally perturbed segments include the majority of loop regions, as well as the α1 and α2 helices. A significant decrease in the α1-α2 inter-helical angle observed across the simulation trajectory leads to closer helical packing at their C-termini. The end-simulation conformations of the prestin and pendrin STAS domains, including their decreased α1-α2 inter-helical angles, resemble more closely the packing of corresponding helices in the STAS structures of bacterial SulP transporters Rv1739c and ychM, as well as those of the anti-sigma factor antagonists. Several structural segments of the modeled human pendrin STAS domain exhibit larger atomic motions and greater conformational deviations than the corresponding regions of rat prestin, predicting that the human pendrin STAS domain in solution structure may be more dynamic than rat prestin STAS. Regions of prestin and pendrin identified by RMS fluctuation data as exhibiting larger atomic fluctuations corresponded to nominal GDP-binding regions of the aligned Rv1739c STAS domain of M. tuberculosis. Conclusions: MD simulations of mammalian STAS domains reveal substantial predicted conformational heterogeneity. These predicted conformational dynamics serve to supplement the reported crystal structure of the rat prestin STAS domain, and extend our understanding of the roles of STAS domains in SLC26 anion transporter function.

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Pendrin Function and Regulation in <i>Xenopus</i> Oocytes

Cited by 29 publications

References 71 publications

N-glycosylation and topology of the human SLC26 family of anion transport membrane proteins

N-glycosylation and topology of the human SLC26 family of anion transport membrane proteins

The ESF Meeting on „The Proteomics, Epigenetics and Pharmacogenetics of Pendrin“

Molecular Dynamics Simulations of the STAS Domains of Rat Prestin and Human Pendrin Reveal Conformational Motions in Conserved Flexible Regions

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