title: Protein 4.2 is critical to CD47-membrane skeleton attachment in human red cells.
abstract: The reduction in expression of the integral membrane protein CD47 in human red blood cells (RBCs) deficient in protein 4.2 suggests that protein 4.2 may mediate a linkage of CD47 to the membrane skeleton. We compared the fractions of membrane skeleton-attached CD47, Rh-associated glycoprotein (RhAG), Rh, and band 3 in normal and protein 4.2-deficient cells using fluorescence-imaged microdeformation. We found that CD47 attachment decreases from 55% in normal cells to 25% to 35% in 4.2-deficient cells. RhAG, which has been shown to have no significant variation in expression among the cells studied, shows a significant decrease in membrane skeleton attachment in 4.2-deficient cells from 60% to 40%. Both Rh and band 3, which have also been shown to have no change in expression, show a smaller decrease from 75% attached in normal RBCs to 55% attached in 4.2-deficient cells. In normal cells, Rh phenotype influences CD47 expression but not the level of membrane skeleton attachment of CD47. In contrast, the results indicate that protein 4.2 strongly influences CD47 levels as well as the extent of membrane skeleton attachment in the RBC, whereas protein 4.2 affects membrane skeletal attachment of RhAG, Rh, and band 3 to a lesser extent.
authors.affiliation: Department of Chemical and Biomolecular Engineering and School of Engineering and Applied Science, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Kris Noel
authors.initials: KN
authors.lastname: Dahl
authors.forename: Ranganath
authors.initials: R
authors.lastname: Parthasarathy
authors.forename: Connie M
authors.initials: CM
authors.lastname: Westhoff
authors.forename: D Mark
authors.initials: DM
authors.lastname: Layton
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Discher
mesh_terms: D000199:Actins / Q000097:blood; D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D015703:Antigens, CD / Q000097:blood*; D001798:Blood Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051928:CD47 Antigen; D002352:Carrier Proteins / Q000097:blood*; D002448:Cell Adhesion; D002454:Cell Differentiation; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000276:immunology / Q000378:metabolism; D004907:Erythrocyte Deformability; D004910:Erythrocyte Membrane / Q000276:immunology* / Q000378:metabolism*; D004912:Erythrocytes / Q000166:cytology; D006801:Humans; D066298:In Vitro Techniques; D008565:Membrane Proteins; D009154:Mutation; D012204:Rh-Hr Blood-Group System / Q000378:metabolism; D013049:Spectrin / Q000378:metabolism
chemical_list: D000199:Actins; D001457:Anion Exchange Protein 1, Erythrocyte; D015703:Antigens, CD; D001798:Blood Proteins; D051928:CD47 Antigen; C497894:CD47 protein, human; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D012204:Rh-Hr Blood-Group System; C044791:erythrocyte membrane band 4.2 protein; D013049:Spectrin