Protein isoforms in RBC membranes. (A) The splice isoforms of membrane proteins are summarized with the relevant peptides that permitted unequivocal attribution to a specific isoform when such attribution was possible. (B) The partial of a Clustal W alignment of sister proteins is shown for the glucose transporters of RBCs as an example of the way by which we ensured the presence of specific peptides for each protein in the final data set. The evidenced peptides were found (among others) and are clearly unique to each protein.