Organisation of the mouse <i>Gnas</i> locus.

<p>Both the maternally and paternally inherited copies of the <i>Gnas</i> cluster are shown. Boxes represent exons. The solid black filled boxes represent first exons of the protein-coding transcripts <i>Nesp</i>, <i>Gnas</i> and <i>Gnasxl</i> (labelled XL) whereas shaded boxes are first exons of the non-coding transcripts <i>Nespas</i> and <i>Exon1A</i> (labelled 1A). Arrows show the direction of transcription. <i>Gnas</i> expression is shown as a dotted line as <i>Gnas</i> itself shows tissue-specific imprinted expression. The position of the differentially methylated regions (DMRs) is shown by a string of filled circles on the allele on which the DMR is methylated. <i>Nesp</i> transcription traverses the entire length of the cluster, including the <i>Nespas-Gnasxl</i> DMR and the <i>Exon1A</i> DMR, as shown by a long arrow. The figure is not to scale. Adapted from Williamson <i>et al</i> (2011).