This family consists of several eukaryotic transcription elongation Spt5 proteins. These proteins contain two copies of a domain (Supt5; ) that is characteristic of proteins involved in chromatin regulation. An NGN domain separates the Supt5 domains. In yeast Spt5 protein, this domain possesses a RNP-like fold and it is thought to confer affinity for Spt4 protein. Supt5 domains are followed by four to five copies of a KOW domain (), present in many ribosomal proteins.Three transcription-elongation factors Spt4, Spt5, and Spt6 are conserved among eukaryotes and are essential for transcription via modulation of chromatin structure. Spt4 and Spt5 are tightly associated in a complex, while the physical association Spt6 is considerably weaker. It has been demonstrated that Spt4, Spt5, and Spt6 play roles in transcription elongation in both yeast and humans, including a role in activation by Tat. 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 [].This information was partially derived from InterPro ().
