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. 2024 Sep 25;11(9):240790. doi: 10.1098/rsos.240790

Figure 4.

mRNA splice variants of human TAF1 in the literature.

mRNA splice variants of human TAF1 in the literature. (a) TAF1 genomic DNA region (Xq13.1) including human TAF1 exons 30–38 that have been found in mRNAs (5′ exons 1–29 are not shown). Alternative exons 32′, 34′ and 35′ and exons 35 a/b are shown in genomic DNA at their positions relative to canonical exons. TAF1 is transcribed on the sense strand and ING2 is transcribed downstream of TAF1 in an antisense orientation. OGT is transcribed in a sense orientation downstream. In older literature, d exons 1–5, shown in grey, were described as located downstream of TAF1 [31] but whether they are spliced with canonical TAF1 exons is yet to be robustly demonstrated. (b,c) mRNA variants described by Capponi et al. involving exon 30–38 taken from sequenced brain transcripts [30]. (b) Canonical TAF1 (cTAF1, TAF1−204). (c) Nine further TAF1 variants resulting from alternative splicing where (i) alternative exons 32′, 34′ and/or 35′ are incorporated; (ii) exon 33 is skipped in the cTAF1 transcript or (iii) alternative exon 35b is incorporated into the TAF1 transcript instead of 35a. Exons and introns are not to scale. Data were obtained from long-range reverse transcription-polymerase chain reaction (RT-PCR) in which the amplicon spanned between exons 30 and 38. Whether canonical TAF1 exons 1−29 are present upstream of exons 30–38 cannot be confirmed, because of lack of upstream sequencing data from the transcripts other than cTAF1. We speculate on the presence of TAF1−203/variant 2 in NCBI (which is identical to cTAF1 apart from exon 5 which is not included in the sequencing), nTAF1 (TAF1−201/variant 3), TAF1−226 and TAF1−221. (d) mRNA variants shown are based on phage-cloned DNA and RT-PCR analyses. Variants 1−2i include TAF1 exons, whereas variants 3 and 4 are transcribed independently of TAF1. Nolte et al. investigated transcripts using primers designed between exon 30 and d4, whereas Herzfeld et al. investigated transcripts using primers designed between TAF1 exon 26 and d3. Variants identified by Nolte et al. and Herzfeld et al. were identified in the human foetal brain and caudate nucleus [31,32]. Created with BioRender.com.