Structure of hRPB11 genes, mRNAs and proteins. A) Comparison of the structures of hRPB11a and b genomic sequences. Horizontal lines represent the human genomic sequences. The identified exons are indicated by boxes. The conserved 5' sequences encompassing exons 1–3 are in black. The homologies between subtypes a and b are indicated. The divergent 3' regions are hatched. A representative metaphase that has been hybridised with a hRPB11a genomic probe (bracket) is shown on the right. The white arrowheads point to the position of the specifically bound loci. Chromosome 7 is represented with brackets pointing to the identified localisations. B) Structure of hRPB11a, bα and bβ mRNAs. Exons are indicated by boxes. Carets represent the spliced introns approximate sizes (bp). The 5' and 3' untranslated regions are shown as open boxes. The size (bp) of the coding sequence (CDS) present in each exon is indicated below. C) Aminoacid sequences of hRPB11a, bα and bβ polypeptides. The translated CDS of the mRNA identified for the two genes shown above are aligned with their identity and size (aminoacids) indicated on the left and right, respectively. The limits of the exons encoding each part of the sequence are indicated by brackets, with the corresponding exon numbers indicated above. The sequence of hRPB11a being taken as a reference, only the divergent residues are shown underneath. Saccharomyces cerevisiae RPB11 (ScRPB11) sequence is shown below.