HMG-proteins 1 and 2 are required for transcription of chromatin by endogenous RNA polymerase

An androgen receptor was isolated and partially purified from the cytosol fraction of ram seminal vesicles. An almost two thousand fold purification with a recovery of 33% could be obtained by chromatography on 2′,5′-ADP-sepharose, ammoniumsulphate precipitation and gel filtration on Ultrogel ACA-44. The labelled receptor was characterized by electrophoresis and sucrose gradient centrifugation (sedimentation at approximately 3S). The purified receptor has a DNA binding-site and is specific for androgenic steroids.     

Two regions of an avian hepadnavirus RNA pregenome are required in cis for encapsidation.

We have constructed a series of deletion mutants spanning the genome of duck hepatitis B virus in order to determine which regions of the viral genome are required in cis for packaging of the pregenome into capsid particles. Deletion of sequences within either of two nonadjacent regions prevented replication of the mutant viral genomes expressed in a permissive avian hepatoma cell line in the presence of functionally active viral core and P proteins. Extraction of RNA from cells transfected with these replication-defective mutants showed that the mutants retained the capacity to be transcribed into a pregenomic-size viral RNA, but that these RNA species were not packaged into viral capsids. The two regions defined by these deletions are located 36 to 126 (region I) and 1046 to 1214 (region II) nucleotides downstream of the 5' end of the pregenome and contain sequences which are required in cis for encapsidation of the duck hepatitis B virus pregenome.