Figure 1

Factors involved in alternative pre-mRNA splicing. (A) Co-localisation of the antagonistic splicing factors SF2/ASF and hnRNPA1 within the nuclei of human myometrial cells by fluorescence confocal microscopy; Nuclei (blue) were defined by staining with 4',6-diamidino-2-phenylindole (DAPI) which binds to double stranded DNA; Co-localisation of SF2/ASF (green fluorescence) and hnRNPA1 (red fluorescence) was observed using monoclonal antibodies specific to each protein. (B) Regulation of alternative pre-mRNA splicing involves many different nuclear trans-acting splicing factors (SF), such as SR protein members, e.g SF2/ASF and hnRNPs, e.g hnRNPA1 and snRNPs that recognise and interact with numerous cis-acting RNA motifs present within the pre-mRNA sequence of genes; these include 5'donor and 3'acceptor sites at exon: intron boundaries, exon and intron enhancer elements (ESE, ISE) which can promote the use of specific splice sites; exon and intron silencer elements (ESS, ISS) which can when bound by hnRNPs repress the use of specific splice sites. Coloured boxes represent alternatively spliced exons.