Autoregulation of mouse BMP-2 gene transcription is directed by the proximal promoter element

The prion proteins (PrP) from sheep and mouse were produced in large quantities of full-length protein in Escherichia coli after fusion with a carboxy-terminal hexahistidine sequence. Both recombinant proteins were recognized, at variable levels, in ELISA using a panel of antibodies recognizing different parts of the PrP molecules, from the octo-repeat region (79-92 human sequence), to the C terminal end of the protein. We show that these recombinant proteins enable polyclonal antisera to be produced in PrP0/0 mice, the sheep prion protein being strongly immunogenic, using either native or guanidium hydrochloride-treated recombinant protein. Sera produced against the sheep protein also reacted in Western blot with bovine, ovine, and murine PrP res, but showed higher reactivity with sheep PrP res. Interestingly, when compared to an antiserum produced against bovine 106-121 peptidic sequence (RB1), we found strikingly different ratios of the PrP res glycoforms, in both cattle with BSE and sheep with natural scrapie, but not in scrapie infected mice. Such results further demonstrate that the assessment of PrP res glycoform ratios, using different antibodies, may depend on antibodies species-specificities.     

Identification of a promoter element located upstream from the hepatitis B virus X gene.

We have analyzed a series of plasmids in which the sequences located upstream from the hepatitis B virus (HBV) X gene were linked to the chloramphenicol acetyl transferase (CAT) gene. Expression of the marker CAT gene in transfected cells clearly demonstrated that sequences preceding the X gene contain an active promoter. RNA mapping by primer extension indicated that the RNA encoded by the X gene promoter initiates at multiple sites spanning nucleotides 1250 to 1350 on the HBV genome. Deletion within the adjacent HBV enhancer element region significantly reduced the activity of the X gene promoter, suggesting that the X gene promoter requires the enhancer element for maximal activity.