Flip/flop splice variants

Fig. 2. Distribution of AMPA receptor flip and flop splice variant mRNAs in the adult rat brain (X-ray film autoradiographs, sagittal sections), cb. cerebellum cpu, caudate putamen ctx, netKorlex dg. dentate granule cells ob, olfactory bulb (Sommer et al.. 1990 Wisden, Seeburg and Monyer, unpublished). Scale bar. 10 mm.

Genetic regulation via splice variants and RNA editing further increases receptor heterogeneity the flip/flop versions and the Q/R site 279... 

Genetic regulation via splice variants and RNA editing further increases receptor heterogeneity the flip/flop versions and the Q/R site. Splice variants that impart functional differences and/or different cellular expression patterns have been found for most of the glutamate receptor subunits. The first splice variants to be described were the so-called flip and flop versions of the AMPA... 

Similar to NR1, alternative splicing of the AMPA receptor, which determines receptor desensitization, may also be altered in schizophrenia (Stine et al., 2001). However, in a recent study by O Connor and colleagues (2007), transcripts for the flip/flop variants of all four AMPA receptor subunits were measured in DLPFC from patients with schizophrenia by quantitative PCR, and no changes in these isoforms were identified in two different patient samples. 

The flip and flop mRNA splice variants appear at different times during development. The flop versions are expressed at low levels prior to postnatal day 8 their characteristic high expression in CAl pyramidal cells becomes apparent only during the second postnatal week (Fig. 16) (Monyer et al., 1991). In contrast, flip RNA levels are already substantial in pyramidal cells from birth (Monyer et al., 1991). As the CAl pyramidal cells mature, the recruitment of the flop cassette into the AMPA receptors may cause these receptors to ipactivate faster (Mosbacher et al., 1994). 

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