title: The p95-100 kDa ligand of the T cell-specific adaptor (TSAd) protein Src-homology-2 (SH2) domain implicated in TSAd nuclear import is p97 Valosin-containing protein (VCP).
abstract: T cell-specific adapter protein (TSAd) is required for normal T cell antigen receptor (TCR)-induced transcription of cytokine genes in T cells. How TSAd controls cytokine transcription is unknown. Previously, we have shown that TSAd is actively transported to the nucleus of T cells suggesting that this adapter may in part function within this cellular compartment. Nuclear translocation of TSAd is dependent upon an intact Src-homology-2 (SH2) domain and a p95-100 kDa ligand of the SH2 domain has been implicated in nuclear import. Here, using microchemical techniques, we identify p95-100 as p97 Valosin-containing protein (VCP) whose homolog in yeast is the cell division control protein, CDC48. Physical interaction between TSAd and VCP can be demonstrated between endogenous proteins in T cells. Interaction is direct and is dependent upon phosphorylation of tyrosine residue 805 of VCP that has been previously recognized as a major target of tyrosine kinase(s) involved in TCR signaling. Significantly, with the use of CDC48 mutant yeast, we demonstrate that VCP/CDC48 is required for transport of TSAd into the eukaryotic nucleus. These findings provide important insights into the mechanism of TSAd nuclear import and the role of TSAd in T cell signal transduction.
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, 6606 Medical Science Building II, Ann Arbor, Michigan 48109-0620, USA.
authors.forename: Francesc
authors.initials: F
authors.lastname: Marti
authors.forename: Philip D
authors.initials: PD
authors.lastname: King
mesh_terms: D021581:Active Transport, Cell Nucleus; D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000251:Adenosine Triphosphatases; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D013601:T-Lymphocytes / Q000378:metabolism*; D000074405:Valosin Containing Protein; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D008024:Ligands; D019000:Phosphotyrosine; D000251:Adenosine Triphosphatases; C000614178:VCP protein, human; D000074405:Valosin Containing Protein