Predominant mucosal expression of 5-HT4(+h) receptor splice variants in pig stomach and colon

Figure 1 Schematic representation. A: The porcine and human 5-HT₄ receptor splice variants; B: cDNA of the porcine 5-HT_4(hb) receptor based on gene browsing (transcript ID: ENSSSCT00000015770 on http://www.ensembl.org/Sus_scrofa/Gene). The 5-HT₄ receptor variants have identical sequences up to Leu³⁵⁸, or Leu³⁷² when exon h is included, and differ by the length and composition of their C-terminal domain. The presence of the h sequence of 14 amino acids in the second extracellular loop depends on the all or none inclusion of exon h between exon 4 and 5. The positions of the boundaries in between exons, the transmembrane (TM) domains IV and V and the positions of primers used in this study are indicated. The primers will detect all 5-HT₄ receptor splice variants. Amplification will result in a 277 bp amplicon, when containing the 42 bp h-exon or a 235 bp amplicon, not containing the h-exon.