DETERMINATION OF FUNCTIONAL DOMAINS IN POLYPYRIMIDINE-TRACT-BINDING PROTEIN

Polypyrimidine-tract-binding protein (PTB) is involved in pre-mRNA spl icing and internal-ribosomal-entry-site-dependent translation. The bio chemical properties of various segments of PTB were analysed in order to understand the molecular basis of the PTB functions. The protein ex ists in oligomeric as well as monomeric form. The central part of PTB (amino acids 169-293) plays a major role in the oligomerization. PTB c ontains several RNA-binding motifs. Among them, the C-terminal part of PTB (amino acids 329-530) exhibited the strongest RNA-binding activit y. The N-terminal part of PTB is responsible for the enhancement of RN A binding by HeLa cell cytoplasmic factor(s).