Combining restriction digestion and touchdown PCR permits detection of trace isoforms of histamine H3 receptor.

The conserved sequences of the mouse histamine H3 receptor at the potential alternative splice junctions suggest that the splice isoforms found in guinea pig, rat, human, and hamster may also be present in the mouse. However, the trace amount isoforms are hard to be detected by the regular PCR approach. In this paper, we report a method in which the unspliced long isoform is cut by restriction endonuclease so that the short isoforms can be amplified to detectable levels to confirm the existence of the splice isoforms of H3 receptor mRNA in the mouse. This method is applicable to the detection of trace amounts of splice isoforms that coexist with the long, more abundant isoforms.