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| RECONSTITUTION OF FUNCTIONAL WATER CHANNELS IN LIPOSOMES CONTAINING PURIFIED RED-CELL CHIP28 PROTEIN |
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| Author(s): ZEIDEL ML, AMBUDKAR SV, SMITH BL, AGRE P |
| Source: BIOCHEMISTRY Volume: 31 Issue: 33 Pages: 7436-7440 Published: AUG 25 1992 |
| Times Cited: 327 References: 25 |
| 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, P(f) [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 P(f) which is up to 50-fold above that of control liposomes, but permeability to urea and protons is not increased. Like intact RBC, the P(f) 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 x 10(-14) cm3/s per CHIP28) corresponds to the known P(f) 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. |
| Document Type: Article |
| Language: English |
Addresses:
1. JOHNS HOPKINS UNIV, SCH MED, DEPT CELL BIOL ANAT, BALTIMORE, MD 21205 USA
2. JOHNS HOPKINS UNIV, SCH MED, DEPT PHYSIOL, BALTIMORE, MD 21205 USA
3. VET AFFAIRS MED CTR, MED SERV, BOSTON, MA 02132 USA
4. HARVARD UNIV, BRIGHAM & WOMENS HOSP, SCH MED, DEPT MED, BOSTON, MA 02132 USA
5. HARVARD UNIV, CHILDRENS HOSP, SCH MED, BOSTON, MA 02132 USA |
| Publisher: AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 |
| Subject Category: Biochemistry & Molecular Biology |
| IDS Number: JK533 |
| ISSN: 0006-2960 |
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