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Blood, 15 January 2007, Vol. 109, No. 2, pp. 603-609. Prepublished online as a Blood First Edition Paper on September 28, 2006; DOI 10.1182/blood-2006-05-024091. This Article Full Text (PDF) Supplemental Table and Figures All Versions of this Article: blood-2006-05-024091v1 109/2/603    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 Luo, S.-Z. Articles by Li, R. Search for Related Content PubMed PubMed Citation Articles by Luo, S.-Z. Articles by Li, R. Related Collections Related Article in Blood Online Social Bookmarking                   What's this?  Previous Article  |  Next Article  Submitted May 18, 2006 Accepted August 16, 2006 Glycoprotein Ib forms disulfides with two glycoprotein Ib subunits in the resting platelet Shi-Zhong Luo, Xi Mo, Vahid Afshar-Kharghan, Sankaranarayanan Srinivasan, José A. López, and Renhao Li* Center for Membrane Biology, University of Texas Health Science Center at Houston, Houston, TX, USA Dept. of Medicine, Baylor College of Medicine, Houston, TX, USA Puget Sound Blood Center, Division of Hematology, University of Washington, Seattle, WA, USA * Corresponding author; email: renhao.li{at}uth.tmc.edu. It is widely accepted that glycoprotein (GP) Ib contains one Ib and one Ib subunit that are connected by a disulfide. It is unclear which Cys residue in Ib, C484 or C485, forms the disulfide with Ib. Using mutagenesis studies in transfected CHO cells, we found that both C484 and C485 formed a disulfide with C122 in Ib. In the context of isolated peptides containing the Ib or Ib transmembrane domain and nearby Cys residue, C484 and C485 in the Ib peptide were both capable of forming a disulfide with the Ib peptide. Furthermore, co-immunoprecipitation of epitope-tagged subunits showed that at least two Ib but only one Ib and one IX subunit were present in the GP Ib-IX complex. Finally, the size difference between GP Ib from transfected CHO cells and human platelets was attributed to a combination of sequence polymorphism and glycosylation difference in Ib, not the number of Ib subunits therein. Overall, these results demonstrate that Ib is covalently connected to two Ib subunits in the resting platelet, necessitating revision of the subunit stoichiometry of the GP Ib-IX-V complex. The 2 composition in GP Ib may provide the basis for possible disulfide rearrangement in the receptor complex. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? Related Article in Blood Online: How complex is the platelet GP Ib complex? Kenneth J. Clemetson Blood 2007 109: 393-394. [Full Text] [PDF] This article has been cited by other articles: D. Varga-Szabo, I. Pleines, and B. Nieswandt Cell Adhesion Mechanisms in Platelets Arterioscler. Thromb. Vasc. Biol., March 1, 2008; 28(3): 403 - 412. [Abstract] [Full Text] [PDF]

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