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Blood, 1 March 2004, Vol. 103, No. 5, pp. 1912-1919. Prepublished online as a Blood First Edition Paper on October 16, 2003; DOI 10.1182/blood-2003-03-0928. This Article Full Text (PDF) All Versions of this Article: 2003-03-0928v1 103/5/1912    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Lee, J. C-M Articles by Chasis, J. A. Search for Related Content PubMed PubMed Citation Articles by Lee, J. C-M Articles by Chasis, J. A. Social Bookmarking                   What's this? Submitted March 26, 2003 Accepted September 30, 2003 Mechanism of protein sorting during erythroblast enucleation: role of cytoskeletal connectivity James C-M Lee, J Aura Gimm, Annie J Lo, Mark J Koury, Sharon W Krauss, Narla Mohandas, and Joel Anne Chasis* Department of Biological Engineering, University of Missouri, Columbia, MO, USA Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA Department of Medicine, Vanderbilt University, Nashville, TN, USA The New York Blood Center, New York, NY, USA * Corresponding author; email: jachasis{at}lbl.gov. During erythroblast enucleation, nuclei surrounded by plasma membrane separate from erythroblast cytoplasm. A key aspect of this process is sorting of erythroblast plasma membrane components to reticulocytes and expelled nuclei. Although it is known that cytoskeletal elements actin and spectrin partition to reticulocytes, little is understood about molecular mechanisms governing plasma membrane protein sorting. We chose glycophorin A (GPA) as a model integral protein to begin investigating protein sorting mechanisms. Using immunofluorescence microscopy and Western blotting we found that GPA sorted predominantly to reticulocytes. We hypothesized that the degree of skeletal linkage might control the sorting pattern of transmembrane proteins. To explore this hypothesis, we quantified the extent of GPA association to the cytoskeleton in erythroblasts, young reticulocytes and mature erythrocytes using fluorescence imaged microdeformation (FIMD) and observed that GPA underwent dramatic reorganization during terminal differentiation. We discovered that GPA was more connected to the membrane cytoskeleton, either directly or indirectly, in erythroblasts and young reticulocytes than in mature cells. We conclude that skeletal protein association can regulate protein sorting during enucleation. Further, we suggest that the enhanced rigidity of reticulocyte membranes observed in earlier investigations results, at least in part, from increased connectivity of GPA with the spectrin-based skeleton. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: J. A. Chasis and N. Mohandas Erythroblastic islands: niches for erythropoiesis Blood, August 1, 2008; 112(3): 470 - 478. [Abstract] [Full Text] [PDF] J. Isern, S. T. Fraser, Z. He, and M. H. Baron The fetal liver is a niche for maturation of primitive erythroid cells PNAS, May 6, 2008; 105(18): 6662 - 6667. [Abstract] [Full Text] [PDF] S. T. Fraser, J. Isern, and M. H. Baron Maturation and enucleation of primitive erythroblasts during mouse embryogenesis is accompanied by changes in cell-surface antigen expression Blood, January 1, 2007; 109(1): 343 - 352. [Abstract] [Full Text] [PDF] S. Soni, S. Bala, B. Gwynn, K. E. Sahr, L. L. Peters, and M. Hanspal Absence of Erythroblast Macrophage Protein (Emp) Leads to Failure of Erythroblast Nuclear Extrusion J. Biol. Chem., July 21, 2006; 281(29): 20181 - 20189. [Abstract] [Full Text] [PDF]

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