期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 105, 期 23, 页码 8026-8031出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0803225105
关键词
macromolecular complex; cytoskeleton
资金
- NHLBI NIH HHS [HL78826, HL075716, HL31579, P01 HL078826, R01 HL075716, R01 HL031579] Funding Source: Medline
- NIDDK NIH HHS [R01 DK026263, R37 DK026263, DK26263, P01 DK032094, DK32094] Funding Source: Medline
Protein 4.1R (4.1R) is a multifunctional component of the red cell membrane. It forms a ternary complex with actin and spectrin, which defines the nodal junctions of the membrane-skeletal network, and its attachment to the transmembrane protein glycophorin C creates a bridge between the protein network and the membrane bilayer. We now show that deletion of 4.1R in mouse red cells leads to a large diminution of actin accompanied by extensive loss of cytoskeletal lattice structure, with formation of bare areas of membrane. Whereas band 3,,the preponderant transmembrane constituent, and proteins known to be associated with it are present in normal or increased amounts, glycophorin C is missing and XK, Duffy, and Rh are much reduced in the 4.1R-deficient cells. The inference that these are associated with 4.1R was borne out by the results of in vitro pull-down assays. Furthermore, whereas Western blot analysis showed normal levels of band 3 and Kell, flow cytometric analysis using an antibody against the extracellular region of band 3 or Kell revealed reduction of these two proteins, suggesting a conformational change, of band 3 and Kell epitopes. Taken together, we suggest that 4.1R organizes a macromolecular complex of skeletal and transmembrane proteins at the junctional node and that perturbation of this macromolecular complex not only is responsible for the well characterized membrane instability but may also remodel the red cell surface.
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