Transfer of GRP94(Gp96)-associated peptides onto endosomal MHC class I molecules.
GRP94 (gp96)-associated peptides can elicit cellular immune responses, an activity thought to reflect the presence of a cell surface receptor (CD91) on antigen-presenting cells that mediates GRP94 internalization and trafficking to an amenable site for peptide transfer to major histocompatibility complex class I molecules. We report that GRP94 internalized by receptor-mediated endocytosis is trafficked to a Rab5a, CD1 and transferrin-negative, Fc receptor and major histocompatibility complex class I-positive endocytic compartment. Receptor-internalized GRP94 did not access the endoplasmic reticulum of antigen-presenting cells. To identify the site of re-presentation of GRP94-associated peptides, kinetic analyses were performed utilizing GRP94-OVA (SIINFEKL) peptide complexes, with peptide re-presentation assayed with the Kb-SIINFEKL-specific MAb, 25-D1.16. Analyses of the kinetics of re-presentation of GRP94-associated peptides, under conditions in which de novo synthesis of major histocompatibility complex class I molecules was inhibited, identified a post-endoplasmic reticulum compartment, accessed by mature major histocompatibility complex class I, as the predominant site of GRP94-associated peptide exchange onto major histocompatibility complex class I.
Berwin
B
B
Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
Rosser
M F N
MF
Brinker
K G
KG
Nicchitta
C V
CV
D000595:Amino Acid Sequence; D000818:Animals; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010455:Peptides / Q000378:metabolism*
D018840:HSP70 Heat-Shock Proteins; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D010455:Peptides; C018551:glucose-regulated proteins