Purification and partial characterization of the erythrocyte Kx protein deficient in McLeod patients.
A 37-kDa protein was immunopurified from human erythrocytes as a complex with a monoclonal antibody directed against the Kell blood group protein of 93 kDa. A rabbit antibody raised against the purified complex reacted on a Western blot with the 93-kDa and 37-kDa proteins and was able to immunoprecipitate the 37-kDa component from K0 erythrocytes which express large amount of the Kx antigen, but not from erythrocytes of patients suffering from McLeod syndrome, a X-linked disorder in which the Kx antigen is lacking. Additional studies have shown that the 37-kDa protein is not glycosylated, and permitted the sequence of the 22 first N-terminal amino acids to be established. This sequence was identical to the predicted protein product of the XK gene cloned recently, which is deleted or mutated in McLeod patients [Ho, M., Chelly, J., Carter, N., Danek, A., Crocker, P. & Monaco, A. P. (1994) Cell 77, 869-880]. Our findings provide strong evidence that the 37-kDa red cell membrane protein is identical to the Kx protein produced by the XK structural gene and demonstrate that Kx and Kell proteins are two subunits expressed as a complex hold by disulfide bond(s) at the red cell surface.
Khamlichi
S
S
INSERM U76, Institut National de la Transfusion Sanguine, Paris, France.
Bailly
P
P
Blanchard
D
D
Goossens
D
D
Cartron
J P
JP
Bertrand
O
O
D000595:Amino Acid Sequence; D001798:Blood Proteins / Q000737:chemistry / Q000302:isolation & purification*; D002846:Chromatography, Affinity / Q000379:methods; D004912:Erythrocytes / Q000378:metabolism*; D030342:Genetic Diseases, Inborn / Q000097:blood*; D008040:Genetic Linkage; D006801:Humans; D007106:Immune Sera; D007120:Immunochemistry; D007626:Kell Blood-Group System / Q000276:immunology; D008969:Molecular Sequence Data; D013577:Syndrome; D014960:X Chromosome
D001798:Blood Proteins; D007106:Immune Sera; D007626:Kell Blood-Group System