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C Hovens

Publications and source records attributed to C Hovens.

2 recordsLinked to original sources

Two versatile eukaryotic vectors permitting epitope tagging, radiolabelling and nuclear localisation of expressed proteins.

Two versatile eukaryotic expression vectors have been developed which permit the production of an epitope-tagged cDNA insert by transient transfection in mammalian cells or by in vitro transcription-translation. The first vector, pCATCH, can be used to clone cDNA inserts in three different frames via eight unique restriction sites in a multiple cloning site (MCS) located downstream from both the FLAG epitope and the specific heart muscle kinase phosphorylation site, conferring the possibility of in vitro radiolabelling. A specific protease cleavage site enables the removal of the FLAG epitope, simplifying affinity purification of recombinant CATCH proteins. pCATCH possesses stop codons in all three reading frames at the 3' terminal end of the MCS. A derivate of this vector, pCATCH-NLS, was constructed by incorporating an SV40 nuclear localisation signal upstream from the MCS, for directed localisation of the tagged proteins.

Amino Acid Sequence↗

BZLF1 (ZEBRA, Zta) protein of Epstein-Barr virus selected in a yeast one-hybrid system by binding to a consensus site in the IgH intronic enhancer: a role in immunoglobulin expression?

We have used a yeast one hybrid screen to search for factors interacting with a subsegment of the immunoglobulin heavy chain (IgH) intronic enhancer. The 51 bp enhancer segment harbored a so-called E-box and an octamer site, known to bind helix-loop-helix transcription factors and Oct factors, respectively. Mammalian Oct-2A protein was also expressed in yeast, to select for transcription factors possibly cooperating with Oct-2. Six strongly interacting protein clones were selected from a peripheral blood lymphocyte library. These included a B cell-specific co-activator, termed Bob1, that directly binds to Oct-2 (Gstaiger et al., 1995, Nature 373, 360-362). Three further clones represent the helix-loop factors ITF-1 and ITF-2, another one the nucleolar protein nucleophosmin, or B23. Unexpectedly, the sixth clone with strong activity encoded the BZLF1 (= ZLF1, zta, ZEBRA, EB1) protein of Epstein-Barr virus (EBV). BZLF1 is a leucine zipper-related transcription factor and induces the switch from viral latency to lytic growth. We found that BZLF1 also activated transcription in transiently transfected mammalian cells via a consensus binding site located within the IgH intron enhancer. BZLF1 may thus influence immunoglobulin heavy chain expression in EBV-infected B lymphocytes.

Consensus Sequence↗