Fig. 1

The GRIN2A gene has two transcript variants in human and primate but not mouse brain. a A short isoform of GRIN2A transcript was predicted by open reading frame studies. The published sequence of GRIN2A-S suggests that the final exon (exon 13) is missing two nucleotide regions compared to the canonical transcript: firstly, the lack of 343 nucleotides generates a putative exon 14 in GRIN2A-S (splice site shown in A_i) and the final 206 nucleotides of the canonical form are lost altogether. We designed primers to amplify the region of variance between the two isoforms (Fig. 1, Fw1/Rv1) generating an amplicon of 474 bp in GRIN2A and 131 bp in GRIN2A-S. A second reverse primer was designed to amplify canonical GRIN2A selectively (Fig. 1a, Rv2) generating an amplicon of 380 bp. b-f RT-PCR amplification end products. Control conditions indicate no cDNA template was used in PCR b In human cDNA, only the short form of GRIN2A was observed likely due to preferential amplification in PCR, whereas only a long product of 474 bp was seen in mouse using either human or mouse specific primers. c The Fw1/Rv2 primer pair was used to confirm expression of canonical GRIN2A in the same human sample as shown in (B). d 3 other human cortical samples with GRIN2A-S amplified. e Both the short and long amplicons were observed in human foetal cDNA. f GRIN2A-S was observed in primate (Rhesus) brain cDNA. g Sequencing of human and primate RT-PCR short amplicons confirmed the presence of the putative splice site shown in Ai