Reconstitution of functional water channels in liposomes containing purified red cell CHIP28 protein

Mark L. Zeidel, Suresh V. Ambudkar, Barbara L. Smith, Peter C Agre

Research output: Contribution to journalArticle

Abstract

Water rapidly crosses the plasma membranes of red blood cells (RBCs) and renal tubules through highly specialized channels. CHIP28 is an abundant integral membrane protein in RBCs and renal tubules, and Xenopus laevis oocytes injected with CHIP28 RNA exhibit high osmotic water permeability, Pf [Preston et al. (1992) Science 256, 385-387]. Purified CHIP28 from human RBCs was reconstituted into proteoliposomes in order to establish if CHIP28 is itself the functional unit of water channels and to characterize its physiological behavior. CHIP28 proteoliposomes exhibit Pf which is up to 50-fold above that of control liposomes, but permeability to urea and protons is not increased. Like intact RBC, the Pf of CHIP28 proteoliposomes is reversibly inhibited by mercurial sulfhydryl reagents and exhibits a low Arrhenius activation energy. The magnitude of CHIP28-mediated water flux (11.7 × 10-14 cm3/s per CHIP28) corresponds to the known Pf of intact RBCs. These results demonstrate that CHIP28 protein functions as a molecular water channel and also indicate that CHIP28 is responsible for most transmembrane water movement in RBCs.

Original languageEnglish (US)
Pages (from-to)7436-7440
Number of pages5
JournalBiochemistry®
Volume31
Issue number33
StatePublished - 1992

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Aquaporin 1
Aquaporins
Liposomes
Blood
Erythrocytes
Cells
Water
Permeability
Water Movements
Kidney
Sulfhydryl Reagents
Xenopus laevis
Cell membranes
Oocytes
Urea
Protons
Membrane Proteins
Activation energy
Cell Membrane
RNA

ASJC Scopus subject areas

  • Biochemistry

Cite this

Reconstitution of functional water channels in liposomes containing purified red cell CHIP28 protein. / Zeidel, Mark L.; Ambudkar, Suresh V.; Smith, Barbara L.; Agre, Peter C.

In: Biochemistry®, Vol. 31, No. 33, 1992, p. 7436-7440.

Research output: Contribution to journalArticle

Zeidel, Mark L. ; Ambudkar, Suresh V. ; Smith, Barbara L. ; Agre, Peter C. / Reconstitution of functional water channels in liposomes containing purified red cell CHIP28 protein. In: Biochemistry®. 1992 ; Vol. 31, No. 33. pp. 7436-7440.
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