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Intracellular trafficking pathway of newly synthesized CD1b molecules

V. Briken, R.M. Jackman, S. Dasgupta, S. Hoening, S.A. Porcelli

Author Affiliations

  1. V. Briken1,
  2. R.M. Jackman1,
  3. S. Dasgupta2,
  4. S. Hoening3 and
  5. S.A. Porcelli*,1
  1. 1 Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
  2. 2 Department of Biochemistry & Biophysics, University of California, San Francisco, CA, 94143‐0534, USA
  3. 3 Georg‐August University, Gosslerstrasse 12d, D‐37073, Göttingen, Germany
  1. *Corresponding author. E‐mail: porcelli{at}aecom.yu.edu
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Abstract

The intracellular trafficking of major histocompatibility complex (MHC) class I and class II molecules has evolved to support their function in peptide antigen presentation optimally. We have analyzed the intracellular trafficking of newly synthesized human CD1b, a lipid antigen‐presenting molecule, to understand how this relates to its antigen‐presenting function. Nascent CD1b was transported rapidly to the cell surface after leaving the Golgi, and then entered the endocytic system by internalization via AP‐2‐dependent sorting at the plasma membrane. A second sorting event, possibly involving AP‐3 complexes, led to prominent accumulation of CD1b in MHC class II compartments (MIICs). Functional studies demonstrated the importance of nascent CD1b for the efficient presentation of a foreign lipid antigen. Therefore, the intracellular trafficking of nascent CD1b via the cell surface to reach MIICs may allow the efficient sampling of lipid antigens present in endocytic compartments.

  • Received September 28, 2001.
  • Revision received December 17, 2001.
  • Accepted January 4, 2002.
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