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RhAG protein of the Rhesus complex is a CO 2 channel in the human red cell membrane
Author(s) -
Endeward Volker,
Cartron JeanPierre,
Ripoche Pierre,
Gros and Gerolf
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.07-9097com
Subject(s) - dids , chemistry , red blood cell , glycoprotein , membrane protein , membrane , band 3 , aquaporin , biochemistry , biophysics , microbiology and biotechnology , biology
We have determined CO 2 permeabilities, P CO2 , of red cells of normal human blood and of blood deficient in various blood group proteins by a previously described mass spectrometric technique. While P CO2 of normal red cells is ~0.15 cm/s, we find in red blood cells (RBCs) lacking the Rh protein complex (Rh null ) a significantly reduced P CO2 of 0.07 cm/s ±0.02 cm/s ( P <0.02). This value is similar to the value we have reported previously for RBCs lacking aquaporin‐1 protein (AQP‐1 null ), suggesting that each of the Rh and AQP‐1 proteins is responsible for ~1/2 of the normal CO 2 permeability of the RBC membrane. Four other blood group deficiencies tested lack diverse membrane proteins but exhibit normal CO 2 permeability. The CO 2 pathway constituted by Rh proteins was inhibitable at pH e = 7.4 by NH 4 Cl with an I 50 of ~10 mM corresponding to an I 50 for NH 3 of ~0.3 mM. The pathway independent of Rh proteins, presumably that constituted by AQP‐1, was not inhibitable by NH 4 Cl/NH 3 . However, both pathways were strongly inhibited by DIDS, which accounts for the marked inhibitory effect of DIDS on normal P CO2 , while in contrast another AE1 inhibitor, DiBAC, does not inhibit P CO2 , although it markedly reduces P HCO3‐ . We conclude that Rh protein, presumably the Rh‐associated glycoprotein RhAG, possesses a gas channel that allows passage of CO 2 in addition to NH 3 .— Endeward, V., Cartron, J.‐P., Ripoche, P., and Gros, G. RhAG protein of the Rhesus complex is a CO2 channel in the human red cell membrane. FASEB J. 22, 64–73 (2008)