Abstract
The Epstein-Barr virus (EBV) latent membrane protein 2A (LMP2A) blocks B-cell receptor (BCR) signal transduction in EBV-immortalized B lymphocytes in vitro. The cytoplasmic amino-terminal domain of LMP2A contains an immunoreceptor tyrosine activation motif (ITAM). ITAMs consist of paired tyrosine and leucine residues and play a central role in signal transduction of the BCR and the T-cell receptor (TCR). To investigate the importance of the LMP2A ITAM, two EBV recombinants were constructed, each containing a tyrosine-to-phenylalanine point mutation at amino acid 74 or 85 within the ITAM of LMP2A. Tyrosine phosphorylation, calcium mobilization, and induction of BZLF1 expression were no longer blocked in the LMP2A ITAM mutant LCLs following BCR cross-linking. In addition, the Syk protein tyrosine kinase (PTK) was unable to bind LMP2A In unstimulated LCLs infected with either of the LMP2A ITAM mutants. Analysis of Syk phosphorylation before and after BCR cross-linking in the LMP2A mutant ITAM LCLs compared with wild-type EBV LCLs indicates a specific role of the LMP2A ITAM on the LMP2A-mediated negative effect on the Syk PTK. These data indicate the importance of the LMP2A ITAM motif in the LMP2A-mediated block on BCR signal transduction and position the role of the Syk PTK as being central to the function of LMP2A.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 241-251 |
| Number of pages | 11 |
| Journal | Virology |
| Volume | 235 |
| Issue number | 2 |
| DOIs | |
| State | Published - Sep 1 1997 |
Funding
Suk Kyeong Lee and Cheryl Miller provided invaluable aide and advice. We are grateful for reagents provided by Lawrence Young, Barbara Frech, Gerhard Laux, Elisabeth Kremmer, and Friedrich A. Grässer. This research was supported by Public Health Service Grant CA62234 (R.L.) from the National Cancer Institute. R.L. is a scholar of the Leukemia Society of America. R.L. is also a recipient of a grant from The Council for Tobacco Research Council.
ASJC Scopus subject areas
- Virology