Insertion and internalization of vasoactive intestinal peptide (VIP) receptors in murine CD4 T lymphocytes.
The specific binding of vasoactive intestinal peptide (VIP) to murine lymphocytes was investigated. CD4 T cells from mesenteric lymph nodes (MLN) bound more 125I-VIP than did unseparated MLN lymphocytes at 37 degrees C, but not at 4 degrees C. The differences between the amount of 125I-VIP bound by the CD4 T cells and unseparated MLN lymphocytes at 37 degrees C depended upon a difference in the amount of the ligand that was internalized by the cells. The rate of insertion of unoccupied VIP receptors from the cytoplasm into the cell membrane (370 receptors/cell/min), the rate constants for internalization of ligand occupied VIP receptors (0.55 min-1) and unoccupied VIP receptors (0.11 min-1), and the rate constant for the elimination of internalized VIP (0.07 min-1) by CD4 T cells were evaluated. These results provide new understanding of the behaviour of VIP receptors on lymphocytes and indicate a mechanism by which CD4 T lymphocytes can homologously regulate their surface expression of VIP receptors in the presence of ambient VIP.
Department of Medicine, St. Michael's Hospital, University of Toronto, Canada.
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Ottaway
D000818:Animals; D001665:Binding Sites; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D005260:Female; D007700:Kinetics; D008198:Lymph Nodes; D008214:Lymphocytes / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D011869:Radioligand Assay; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide
D011964:Receptors, Gastrointestinal Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide