Spt4 is a transcription elongation factor. Three transcription-elongation factors Spt4, Spt5, and Spt6, are conserved among eukaryotes and are essential for transcription via the modulation of chromatin structure. It is known that Spt4, Spt5, and Spt6 are general transcription-elongation factors, controlling transcription both positively and negatively in important regulatory and developmental roles. Spt4 functions entirely in the context of the Spt4-Spt5 heterodimer and it has been found only as a complex to Spt5 in Yeast and Human. Spt4 is a small protein that has zinc finger at the N-terminus. Spt5 is a large protein that has several interesting structural features of an acidic N-terminus, a single NGN domain, five or six KOW domains, and a set of simple C-termianl repeats. Spt4 binds to Spt5 NGN domain. Unlike Spt5, Spt4 is not essential for viability in yeast, however Spt4 is critical for normal function of the Spt4-Spt5 complex. Spt4 homolog is not found in bacteria.