TAFII70 protein in Cajal bodies of the amphibian germinal vesicle.

Abstract

The localization of the TATA-binding protein (TBP) associated factor II70 (TAFII70) in the germinal vesicle (GV) of newt oocytes was investigated. In spreads of GV content, anti-hTAFII70 monoclonal antibody (mAb) stained Cajal bodies (CBs) that were either attached to specific sites on the lampbrush chromosomes or free in the nucleoplasm. To confirm this localization the PwTAFII70 cDNA was cloned and myc-tagged transcripts injected into the oocyte cytoplasm. Newly translated PwTAFII70 protein was detected a few hours later in the Cajal bodies. These data support the hypothesis that Cajal bodies are the assembly sites of the transcription machinery of the oocyte nucleus. TAFII70 protein can play a role in lampbrush transcription; alternatively TAFII70 can be considered a component in the subset of TFIID complexes that do not function during oogenesis, but are accumulated in the oocyte for later use during early development.