Reduced membrane protein methylation in red cells of the McLeod blood group phenotype.
Red cells (RBCs) contain an abundance of protein methylase II, which catalyzes the transfer of methyl groups from S-adenosylmethionine to carboxyl groups of aspartyl and glutamyl residues in proteins. Enzyme-catalyzed transfer of methyl groups, labeled with 14C or 3H, from S-adenosylmethionine to membrane proteins of McLeod, Ko, and control RBCs was assayed by determining the acceptance of labeled methyl groups under standardized conditions. Membranes of control cells and Ko cells showed about 50 percent greater uptake than did those of McLeod cells. However, when ovalbumin was used as a methyl-accepting substrate, the levels of protein carboxymethyltransferase activity in all three types of cells were found not to differ significantly. In addition, no significant qualitative differences were apparent when methyl-labeled polypeptides from control and McLeod cells were separated by slab gel electrophoresis. The mechanisms responsible for changes in membrane protein methylation of McLeod cells remain unclear. However, these observations provide further evidence of the pleiotropic biochemical lesion associated with the acanthocytic morphology that characterizes McLeod RBCs.
Wainfan
E
E
Lindsley F. Kimball Research Institute, New York Blood Center, New York.
Kilkenny
M
M
Johnson
C
C
Marsh
W L
WL
D004910:Erythrocyte Membrane / Q000378:metabolism*; D006801:Humans; D007626:Kell Blood-Group System; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008745:Methylation; D010641:Phenotype
D007626:Kell Blood-Group System; D008565:Membrane Proteins