Gene organization and chromosome mapping of the testis-specific S-II

Transcription elongation factor SII

RNA chain elongation by RNA polymerase II (pol II) is a complex and regulated process which is coordinated with capping, splicing, and polyadenylation of the primary transcript. Numerous elongation factors that enable pol II to transcribe faster and/or more efficiently have been purified. SII is one such factor. It helps pol II bypass specific blocks to elongation that are encountered during transcript elongation. SII was first identified biochemically on the basis of its ability to enable pol II to synthesize long transcripts. ((1)) Both the high resolution structure of SII and the details of its novel mechanism of action have been refined through mutagenesis and sophisticated in vitro assays. SII engages transcribing pol II and assists it in bypassing blocks to elongation by stimulating a cryptic, nascent RNA cleavage activity intrinsic to RNA polymerase. The nuclease activity can also result in removal of misincorporated bases from RNA. Molecular genetic experiments in yeast suggest that SII is generally involved in mRNA synthesis in vivo and that it is one type of a growing collection of elongation factors that regulate pol II. In vertebrates, a family of related SII genes has been identified; some of its members are expressed in a tissue-specific manner. The principal challenge now is to understand the isoform-specific functional differences and the biology of regulation exerted by the SII family of proteins on target genes, particularly in multicellular organisms.

Gene structure and chromosome mapping of mouse transcription elongation factor S-II (Tcea1)

We report the organization and chromosome localization of the mouse transcription elongation factor S-II gene (Tcea1). This gene was found to be a single copy gene consisting of 10 exons spanning approximately 30kb. Its organization was the same as those of the mouse testis-specific S-II gene (Tcea2) and Xenopus general S-II gene (xTFIIS.oA), but different from that of the human S-II gene family. We also identified a processed pseudogene (Tcea1-ps1) with a sequence highly homologous to those of S-II cDNAs but containing a translation termination codon within its open reading frame. Linkage analysis showed that Tcea1 and Tcea1-ps1 are mapped on mouse chromosomes 1 and 15, respectively. Relationships between Tcea1 and S-II cDNAs isolated so far are discussed.