Functional substitution for TAF(II)250 by a retroposed homolog that is expressed in human spermatogenesis.
TAF(II)250, the largest subunit of the general transcription factor TFIID, is expressed from the human X chromosome, at least in somatic cells. In male meiosis, however, the sex chromosomes are transcriptionally silenced, while the autosomes remain active. How then are protein-encoding genes transcribed during human male meiosis? Here we present a novel autosomal human gene, TAF1L, which is homologous to TAF(II)250 and is expressed specifically in the testis, apparently in germ cells. We hypothesize that during male meiosis, transcription of protein-encoding genes relies upon TAF1L as a functional substitute for TAF(II)250. Like TAF(II)250, the human TAF1L protein can bind directly to TATA-binding protein, an essential component of TFIID. Most importantly, transfection with human TAF1L rescued the temperature-sensitive lethality of a hamster cell line mutant in TAF(II)250. TAF1L lacks introns and evidently arose by retroposition of a processed TAF(II)250 mRNA during primate evolution. The observation that TAF1L can functionally replace TAF(II)250 provides experimental support for the hypothesis that during male meiosis, autosomes provide cellular functions usually supplied by the X chromosome in somatic cells.
Wang
P Jeremy
PJ
Howard Hughes Medical Institute, Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA.
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David C
DC
D019143:Evolution, Molecular; D051548:Histone Acetyltransferases; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D009928:Organ Specificity / Q000235:genetics; D017385:Sequence Homology; D013094:Spermatozoa / Q000378:metabolism; D035381:TATA-Binding Protein Associated Factors / Q000235:genetics* / Q000378:metabolism; D035181:TATA-Box Binding Protein / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D035362:Transcription Factor TFIID / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
C472868:TAF1L protein, human; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D051548:Histone Acetyltransferases; C069001:TATA-binding protein associated factor 250 kDa