Kx, a quantitatively minor protein from human erythrocytes, is palmitoylated in vivo.
Kx is a quantitatively minor blood group protein of human erythrocytes which is thought to be a membrane transporter. In the red cell membrane, Kx forms a complex stabilized by a disulfide bond with the Kell blood group membrane protein which might function as a metalloprotease. The palmitoylation status of these proteins was studied by incubating red cells with [3H] palmitic acid. Purification of the Kell-Kx complex, by immunochromatography on an immobilized human monoclonal antibody of Kell blood group specificity demonstrated that the Kx but not the Kell protein is palmitoylated. Six cysteines in Kx are predicted to be intracytoplasmic and might be targets for palmitoylation. Three of these cysteines are present in a portion of sequence which is predicted to form an amphipathic alpha helix. Palmitoylation of one or several of these cysteines might contribute to anchor the cytoplasmic portion of the Kx protein to the inner surface of red cell membrane.
Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, Paris, 75015, France.
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Carbonnet
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Hattab
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Callebaut
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Cochet
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Blancher
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Cartron
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Bertrand
D000595:Amino Acid Sequence; D026921:Amino Acid Transport Systems, Neutral; D001798:Blood Proteins / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D007626:Kell Blood-Group System / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D019308:Palmitic Acid; D011499:Protein Processing, Post-Translational
D026921:Amino Acid Transport Systems, Neutral; D001798:Blood Proteins; D002352:Carrier Proteins; D007626:Kell Blood-Group System; D008565:Membrane Proteins; C087883:XK protein, human; D019308:Palmitic Acid