Kell and Kx, two disulfide-linked proteins of the human erythrocyte membrane are phosphorylated in vivo.
Kell and Kx are two quantitatively minor proteins from the human erythrocyte membrane which carry blood groups antigens and are thought to be a metalloprotease and a membrane transporter, respectively. In the red cell membrane, these proteins form a complex stabilized by disulfide bond(s). Phosphorylation status of these proteins was studied, in the presence or absence of effectors of several kinases, either on intact cells incubated with [32P]-orthophosphate or on ghosts incubated with [gamma-32P]ATP. Purification of Kell-Kx complex, by immunochromatography on an immobilized human monoclonal antibody of Kell blood group specificity allowed to establish that (i) neither protein is phosphorylated on tyrosine; (ii) the Kell protein is a putative substrate for Casein Kinase II (CKII) and Casein Kinase I (CKI) but not for protein kinase C (PKC), whereas Kx protein is phosphorylated by CKII and PKC but not by CKI; (iii) Protein Kinase A neither phosphorylates the Kell nor the Kx proteins.
Carbonnet
F
F
INSERM U76, Institut National de la Transfusion Sanguine, Paris, France.
Hattab
C
C
Cartron
J P
JP
Bertrand
O
O
D000954:Antigens, Surface / Q000737:chemistry*; D047390:Casein Kinase II; D047388:Casein Kinases; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000737:chemistry; D004912:Erythrocytes / Q000737:chemistry*; D006801:Humans; D007626:Kell Blood-Group System / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism
D000954:Antigens, Surface; D004220:Disulfides; D004791:Enzyme Inhibitors; D007626:Kell Blood-Group System; D008565:Membrane Proteins; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D047390:Casein Kinase II; D047388:Casein Kinases; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C