SEARCH:   Advanced

Blood, 1 May 2004, Vol. 103, No. 9, pp. 3440-3447. Prepublished online as a Blood First Edition Paper on January 8, 2004; DOI 10.1182/blood-2003-06-2083. This Article Full Text (PDF) All Versions of this Article: 2003-06-2083v1 103/9/3440    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 Takeda, A. Articles by Yaseen, N. R Search for Related Content PubMed PubMed Citation Articles by Takeda, A. Articles by Yaseen, N. R Social Bookmarking                   What's this? Submitted June 25, 2003 Accepted December 31, 2003 CD45-associated protein inhibits CD45 dimerization and upregulates its protein tyrosine phosphatase activity Akiko Takeda*, Akio Matsuda, Rachelle M Paul, and Nabeel R Yaseen Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA Department of Pathology, Roger Williams Hospital-Boston University, Providence, RI, USA * Corresponding author; email: a-takeda{at}northwestern.edu. CD45, a receptor-like protein tyrosine phosphatase (PTP), plays an essential role in lymphocyte development and immune responses. Recent evidence suggests that dimerization of CD45 downregulates its function. However, the mechanisms by which CD45 dimerization is regulated remain unclear and there is no direct evidence that the PTP activity of CD45 dimers is less than that of monomers. CD45 in lymphocytes associates with CD45-AP (CD45-associated protein). Here we show that T cells from CD45-AP-null mice have a much higher level of CD45 dimers than those of wild-type mice, suggesting that CD45-AP inhibits CD45 dimer formation. This was confirmed using a novel CD45-AP-null T cell line, ALST-1, that we established from a spontaneous thymic tumor found in a CD45-AP-null mouse. Transfected CD45-AP inhibited CD45 dimer formation in ALST-1 cells in proportion to the amount of CD45-AP expressed. Finally, using microsomal fractions from both mouse thymocytes and ALST-1 transfectants, the PTP activity of CD45 was found to be significantly lower in CD45-AP-negative cells than in CD45-AP-positive cells. Therefore, our results support a model in which binding of CD45-AP to inactive CD45 dimers converts them to active monomers. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: S. Lee, C. Faux, J. Nixon, D. Alete, J. Chilton, M. Hawadle, and A. W. Stoker Dimerization of Protein Tyrosine Phosphatase {sigma} Governs both Ligand Binding and Isoform Specificity Mol. Cell. Biol., March 1, 2007; 27(5): 1795 - 1808. [Abstract] [Full Text] [PDF]

	Copyright © 2004 by American Society of Hematology         Online ISSN: 1528-0020