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| ULTRASTRUCTURE, PHARMACOLOGICAL INHIBITION, AND TRANSPORT SELECTIVITY OF AQUAPORIN CHANNEL-FORMING INTEGRAL PROTEIN IN PROTEOLIPOSOMES |
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| Author(s): ZEIDEL ML, NIELSEN S, SMITH BL, AMBUDKAR SV, MAUNSBACH AB, AGRE P |
| Source: BIOCHEMISTRY Volume: 33 Issue: 6 Pages: 1606-1615 Published: FEB 15 1994 |
| Times Cited: 130 References: 48 |
| Abstract: Reconstitution of highly purified aquaporin CHIP (channel-forming integral protein) into proteoliposomes was previously shown to confer high osmotic water permeability (P-f) to the membranes [Zeidel et al. (1992) Biochemistry 31, 7436-7440]. Here we report detailed ultrastructural, pharmacologic, and transport studies of human red cell CHIP in proteoliposomes. Freeze-fracture and transmission electron microscopy revealed a uniform distribution of CHIP which was incorporated into the membranes in both native and inverse orientations. Morphometric analysis of membranes reconstituted at three different concentrations of CHIP revealed that the intramembrane particles correspond to tetramers or possible higher order oligomers, and the P-f increased in direct proportion to the CHIP density. Proteolytic removal of the 4-kDa C-terminal cytoplasmic domain of CHIP did not alter the P-f or oligomerization in red cell membranes. CHIP exhibited a similar conductance for water when reconstituted into membranes of varied lipid compositions. The sensitivities of CHIP-mediated P-f to specific sulfhydryl reagents were identical to known sensitivities of red cell P-f, including a delayed response to p-(chloromercuri) benzenesulfonate. CHIP did not increase the permeability of the proteoliposome membranes to H+/OH- or NH3. These studies demonstrate that CHIP proteoliposomes exhibit all known characteristics of water channels in native red cells and therefore provide a defined system for biophysical analysis of transmembrane water movements. |
| Document Type: Article |
| Language: English |
Addresses:
1. JOHNS HOPKINS UNIV, SCH MED, DEPT BIOL CHEM, BALTIMORE, MD 21205 USA
2. UNIV PITTSBURGH, PRESBYTERIAN UNIV HOSP, SCH MED, DIV RENAL ELECTROLYTE, PITTSBURGH, PA 15261 USA
3. JOHNS HOPKINS UNIV, SCH MED, DEPT MED, BALTIMORE, MD 21205 USA
4. JOHNS HOPKINS UNIV, SCH MED, DEPT PHYSIOL, BALTIMORE, MD 21205 USA
5. UNIV AARHUS, INST ANAT, DEPT CELL BIOL, DK-8000 AARHUS C, DENMARK |
| Publisher: AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 |
| Subject Category: Biochemistry & Molecular Biology |
| IDS Number: MX208 |
| ISSN: 0006-2960 |
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| | | | | | | | | Record from Web of Science® | | | | | | | | | |