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Regulation of epithelial chloride channels by protein phosphatase.

Publication ,  Journal Article
La, BQ; Carosi, SL; Valentich, J; Shenolikar, S; Sansom, SC
Published in: Am J Physiol
June 1991

A combination of planar bilayer and patch-clamp techniques was used to determine whether apical membrane Cl- channels of shark (Squalus acanthias) rectal gland (SRG) were regulated by a phosphorylating and dephosphorylating cycle. In channel reconstitution studies, apical membrane vesicles of SRG were purified, incubated in ATP-Mg2+ and the presence or absence (control) of catalytic subunit of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (cAMP-PK) and incorporated into planar lipid bilayers. In the presence of cAMP-PK, two distinct Cl- channels were found when imposing either 450/50 or 300/50 mM KCl (cis/trans) gradients. The most frequently observed channels (G beta 1) were open greater than 80% at all potentials between -60 and +20 mV (trans ground) and were inactivated by alkaline phosphatase added to the cis chamber. The single-channel conductance of G beta 1 was 42 pS between -60 and +20 mV with a 300/50 mM KCl gradient. The second channel (G beta 2) was always observed in pairs of 62-pS subchannels and was not affected by alkaline phosphatase, but the open probability increased with depolarizing potentials. G beta 2 was observed once, but G beta 1 was never observed in the absence of cAMP-PK. In parallel patch-clamp studies of the apical membrane of cultured SRG, a 50-pS channel similar to G beta 1 was noted after incubating cells with either forskolin, an activator of adenylate cyclase, or okadaic acid, an inhibitor of protein phosphatases 1 and 2A. It is concluded that G beta 1 of SRG can be studied in both patch-clamp and bilayer preparations and that G beta 1 is regulated by reversible phosphorylation by cAMP-PK and dephosphorylation by a protein phosphatase.

Duke Scholars

Published In

Am J Physiol

DOI

ISSN

0002-9513

Publication Date

June 1991

Volume

260

Issue

6 Pt 1

Start / End Page

C1217 / C1223

Location

United States

Related Subject Headings

  • Salt Gland
  • Protein Kinases
  • Phosphoprotein Phosphatases
  • Okadaic Acid
  • Membrane Proteins
  • Lipid Bilayers
  • Kinetics
  • Ion Channels
  • Ethers, Cyclic
  • Dogfish
 

Citation

APA
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La, B. Q., Carosi, S. L., Valentich, J., Shenolikar, S., & Sansom, S. C. (1991). Regulation of epithelial chloride channels by protein phosphatase. Am J Physiol, 260(6 Pt 1), C1217–C1223. https://doi.org/10.1152/ajpcell.1991.260.6.C1217
La, B. Q., S. L. Carosi, J. Valentich, S. Shenolikar, and S. C. Sansom. “Regulation of epithelial chloride channels by protein phosphatase.Am J Physiol 260, no. 6 Pt 1 (June 1991): C1217–23. https://doi.org/10.1152/ajpcell.1991.260.6.C1217.
La BQ, Carosi SL, Valentich J, Shenolikar S, Sansom SC. Regulation of epithelial chloride channels by protein phosphatase. Am J Physiol. 1991 Jun;260(6 Pt 1):C1217–23.
La, B. Q., et al. “Regulation of epithelial chloride channels by protein phosphatase.Am J Physiol, vol. 260, no. 6 Pt 1, June 1991, pp. C1217–23. Pubmed, doi:10.1152/ajpcell.1991.260.6.C1217.
La BQ, Carosi SL, Valentich J, Shenolikar S, Sansom SC. Regulation of epithelial chloride channels by protein phosphatase. Am J Physiol. 1991 Jun;260(6 Pt 1):C1217–C1223.

Published In

Am J Physiol

DOI

ISSN

0002-9513

Publication Date

June 1991

Volume

260

Issue

6 Pt 1

Start / End Page

C1217 / C1223

Location

United States

Related Subject Headings

  • Salt Gland
  • Protein Kinases
  • Phosphoprotein Phosphatases
  • Okadaic Acid
  • Membrane Proteins
  • Lipid Bilayers
  • Kinetics
  • Ion Channels
  • Ethers, Cyclic
  • Dogfish