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P32/TAP, a cellular protein that interacts with EBNA-1 of Epstein-Barr virus.
Virology. 1997 Sep 15; 236(1):18-29.V

Abstract

The Epstein-Barr virus (EBV) EBNA-1 protein has a central role in the maintenance of a latent EBV infection and is the only virus-encoded protein expressed in all EBV-associated tumors. EBNA-1 is required for replication of the episomal form of the latent viral genome and transactivates the latency C and LMP-1 promoters. The mechanisms by which EBNA-1 performs these functions are not known. Here we describe the cloning, expression, and characterization of a cellular protein, P32/TAP, which strongly interacts with EBNA-1. We show that P32/TAP is expressed at high levels in Raji cells and is synthesized as a proprotein of 282 amino acids (aa) that is posttranslationally processed by a two-step cleavage process to yield a mature protein of 209 aa. It has been previously reported that P32/TAP is expressed on the cell surface. Our transient expression assays detected full-length P32/TAP (1-282 aa) in the cytoplasm while mature P32/TAP protein localized to the nucleus. Three lines of evidence support P32/TAP interaction with EBNA-1. First, in the yeast two-hybrid system we mapped two interactive N-terminal regions of EBNA-1, aa 40-60 and aa 325-376, each of which contains arginine-glycine repeats. These regions interact with the C-terminal half of P32/TAP. Second, the full-length cytoplasmic P32/TAP protein can translocate nuclear EBNA-1 into the cytoplasm. Third, P32/TAP co-immunoprecipitated with EBNA-1. We have confirmed that a Gal4 fusion protein containing the C-terminal region of P32/TAP (aa 244-282) transactivates expression from a reporter containing upstream Gal4-binding sites. Deletion of the P32/TAP interactive regions of EBNA-1 severely diminished EBNA-1 transactivation of FRTKCAT in transient expression assays. Our data suggest that interaction with P32/TAP may contribute to EBNA-1-mediated transactivation.

Authors+Show Affiliations

Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21205-2185, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9299613

Citation

Wang, Y, et al. "P32/TAP, a Cellular Protein That Interacts With EBNA-1 of Epstein-Barr Virus." Virology, vol. 236, no. 1, 1997, pp. 18-29.
Wang Y, Finan JE, Middeldorp JM, et al. P32/TAP, a cellular protein that interacts with EBNA-1 of Epstein-Barr virus. Virology. 1997;236(1):18-29.
Wang, Y., Finan, J. E., Middeldorp, J. M., & Hayward, S. D. (1997). P32/TAP, a cellular protein that interacts with EBNA-1 of Epstein-Barr virus. Virology, 236(1), 18-29.
Wang Y, et al. P32/TAP, a Cellular Protein That Interacts With EBNA-1 of Epstein-Barr Virus. Virology. 1997 Sep 15;236(1):18-29. PubMed PMID: 9299613.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - P32/TAP, a cellular protein that interacts with EBNA-1 of Epstein-Barr virus. AU - Wang,Y, AU - Finan,J E, AU - Middeldorp,J M, AU - Hayward,S D, PY - 1997/9/23/pubmed PY - 1997/9/23/medline PY - 1997/9/23/entrez SP - 18 EP - 29 JF - Virology JO - Virology VL - 236 IS - 1 N2 - The Epstein-Barr virus (EBV) EBNA-1 protein has a central role in the maintenance of a latent EBV infection and is the only virus-encoded protein expressed in all EBV-associated tumors. EBNA-1 is required for replication of the episomal form of the latent viral genome and transactivates the latency C and LMP-1 promoters. The mechanisms by which EBNA-1 performs these functions are not known. Here we describe the cloning, expression, and characterization of a cellular protein, P32/TAP, which strongly interacts with EBNA-1. We show that P32/TAP is expressed at high levels in Raji cells and is synthesized as a proprotein of 282 amino acids (aa) that is posttranslationally processed by a two-step cleavage process to yield a mature protein of 209 aa. It has been previously reported that P32/TAP is expressed on the cell surface. Our transient expression assays detected full-length P32/TAP (1-282 aa) in the cytoplasm while mature P32/TAP protein localized to the nucleus. Three lines of evidence support P32/TAP interaction with EBNA-1. First, in the yeast two-hybrid system we mapped two interactive N-terminal regions of EBNA-1, aa 40-60 and aa 325-376, each of which contains arginine-glycine repeats. These regions interact with the C-terminal half of P32/TAP. Second, the full-length cytoplasmic P32/TAP protein can translocate nuclear EBNA-1 into the cytoplasm. Third, P32/TAP co-immunoprecipitated with EBNA-1. We have confirmed that a Gal4 fusion protein containing the C-terminal region of P32/TAP (aa 244-282) transactivates expression from a reporter containing upstream Gal4-binding sites. Deletion of the P32/TAP interactive regions of EBNA-1 severely diminished EBNA-1 transactivation of FRTKCAT in transient expression assays. Our data suggest that interaction with P32/TAP may contribute to EBNA-1-mediated transactivation. SN - 0042-6822 UR - https://www.unboundmedicine.com/medline/citation/9299613/P32/TAP_a_cellular_protein_that_interacts_with_EBNA_1_of_Epstein_Barr_virus_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0042-6822(97)98739-0 DB - PRIME DP - Unbound Medicine ER -