A. Physical Map. The MUC2 locus lies on chromosome 5 between MUC5B and MUC6, and spans 74.5 kb of genomic DNA. B. Gene Structure. We identified an 11,359 bp MUC2 cDNA. Black vertical lines represent the location and relative size of the exons. There are two known assembly gaps in the chicken genome, based on the UCSC Nov 2011 Build (ICGSC Gallus_gallus-4.0/galGal4). Exon 36 (423 bp) is located in the smaller gap, and therefore not included in this figure, as it is unknown where it lies in relationship to its flanking exons. Exon 39 ends blindly in the large (∼21 kb) assembly gap. Exon 40 (29 bp, also not drawn in this map) is located within the gap, and exon 41 is intact on the other side of the gap. The location of these gaps are denoted by large black bars under the gene structure, and gaps are denoted in the genomic structure, when possible (the space between exons 33 and 35 is too small to insert a gap). Exons 34 (198 bp), 38 (44 bp) and 43 (869 bp), which are also not included in this figure) do not fall within the annotated gaps, but are missing in the genomic sequence, indicating errors in the assembly.