CD50 FORUM
This page represents user Comments about PROW Guide on CD50

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Post-transcriptional Modification

From: Johnny T. Stine Date: 02/15/98
Subject: Serine phosphorylation of CD50

• ICAM-3 is serine phosphorylated by PKC (see Enzymes for which this is a Substrate, below).
  
  1. {Hayflick_JS/Gallatin_WM.1997.JBC}
  Hayflick JS, Stine J, Fox R, Hoekstra D, Gallatin WM. 1997. Functional mapping of the cytoplasmic region of intercellular adhesion molecule-3 reveals important roles for serine residues. J Biol Chem 272:22207-22214
  

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From: Johnny T. Stine Date: 02/16/98
Subject: Putative tyrosine phosphorylation of CD50

• Results by Sanchez-Madrid regarding ICAM-3 phosphorylation could not be reproduced in our lab. Under various conditions and methods of TCR activation, only phosphoserine could be detected. Nor could we find any association with fyn or lck. In vitro kinase reactions using the ICAM-3 cyotsolic peptide and fyn kinase purchased from UBI yielded numberous cpm's; however, there was no phosphotyrosine present. Even mutant peptides with the tyrosines mutated showed great cpm. It was later determined that the UBI fyn prep contained large amounts of PKC as shown by western blot. PKC isoforms would phosphorylate the peptide at serine 489. They would not phosphorylate cytosolic tail scrambled peptides nor would they phosphorylate peptides with Ser 489 synthesized as phosphoserine. (Hayflick et al. 1997) One case that did show tyrosine phosphorylation of ICAM-3 used extracellular labelling with 32P gamma ATP. Our cytosolic delete mutant showed labelling on tyrosine indicating that the phosphorylation was occurring on the outside of the cell and was determined to be irrelevant to TCR activation.
  
  1. {Hayflick_JS/Gallatin_WM.1997.JBC}
  Hayflick JS, Stine J, Fox R, Hoekstra D, Gallatin WM. 1997. Functional mapping of the cytoplasmic region of intercellular adhesion molecule-3 reveals important roles for serine residues. J Biol Chem 272:22207-22214
  

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Enzymes for which this is a Substrate

From: Johnny T. Stine Date: 02/16/98
Subject: PKC serine phosphorylates CD50

• Upon T-cell receptor activation, ICAM-3 becomes phosphorylated on Serine residues in a transient manner. PMA also induces the serine phosphorylation of ICAM-3. Experiments using the ICAM-3 cytosolic domain peptide showed that PKC isoforms phosphorylate ICAM-3 in a sequence specific manner on serine 489. These results were published in Hayflick et al. 1997.
  
  1. {Hayflick_JS/Gallatin_WM.1997.JBC}
  Hayflick JS, Stine J, Fox R, Hoekstra D, Gallatin WM. 1997. Functional mapping of the cytoplasmic region of intercellular adhesion molecule-3 reveals important roles for serine residues. J Biol Chem 272:22207-22214
  

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Other Ligands and Associated Molecules

From: Dan Allison Date: 01/02/02
Subject: CD50 binds CD209

• It seems well-established that CD50 (ICAM-3) also binds CD209 (DC-SIGN), a receptor on dendritic cells.
  
  1. {Geijtenbeek_TB/Figdor_CG.2000.CELL}
  Geijtenbeek TB, Torensma R, van Vliet SJ, van Duijnhoven GC, Adema GJ, van Kooyk Y, Figdor CG. 2000. Identification of DC-SIGN, a novel dendritic cell-specific ICAM-3 receptor that supports primary immune responses. Cell 100:575-585
  

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References

From: Joel Hayflick Date: 11/16/99
Subject: CD50 biology and therapeutic target potential

• The following review discusses CD50 (ICAM-3) biology and therapeutic target potential
  
  1. {Hayflick_JS/Gallatin_WM.1998.IR}
  Hayflick JS, Kilgannon P, Gallatin WM. 1998. The intercellular adhesion molecule (ICAM) family of proteins. New members and novel functions. Immunol Res 17:313-327
  

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