Structural analysis of class I MHC molecules: the cytoplasmic domain is not required for cytoskeletal association, aggregation and internalization.
The role of the cytoplasmic domain in a variety of the functional activities of class I MHC molecules has not been documented. To address this question, Jurkat cells were transfected with genes for either native class I MHC molecules or constructs in which all but four cytoplasmic amino acids were deleted. Antibody-induced aggregation and internalization of class I MHC molecules were examined by flow cytometry, and cytoskeletal association was determined by analysing the detergent-resistant fraction of FITC-labeled mAb to class I molecules. The results indicate that the truncated class I MHC molecules are comparable to native class I MHC molecules in the ability to move in the plane of the membrane and aggregate, to associate with the cytoskeleton and to undergo mAb-induced internalization at 37 degrees C. Thus, the cytoplasmic domain of class I MHC molecules is not required for these functional activities.
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The Harold C. Simmons Arthritis Research Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, USA.
Geppert
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Lipsky
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D002449:Cell Aggregation; D003593:Cytoplasm / Q000737:chemistry*; D003599:Cytoskeleton / Q000737:chemistry* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004705:Endocytosis; D015789:HLA-A2 Antigen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000737:chemistry*; D006801:Humans; D019169:Jurkat Cells; D007700:Kinetics; D008970:Molecular Weight; D013329:Structure-Activity Relationship; D014162:Transfection
D015789:HLA-A2 Antigen; D015395:Histocompatibility Antigens Class I