We report the isolation of a cDNA encoding a new type of transcription factor S-II, termed h-SII-T1, from a human library. The mRNA corresponding to the clone is highly expressed in testis and ovary. Comparison of the deduced amino acid (aa) sequence with those of other S-II molecules shows that (i) the C-terminal zinc finger (Zf) domain is highly conserved, and (ii) the central segment is most similar to that of the rat testis-specific S-II. Further analyses of the hS-II-T1 aa sequence indicate that its N-terminal sequence exhibits similarity to eubacterial sigma 54. The significance of tissue-specific S-II molecules for the regulation of transcription elongation is discussed.