IntS9 is a component of integrator complex (INT) which is involved in the small nuclear RNAs (snRNA) U1 and U2 transcription and in their 3'-box-dependent processing. This is the C-terminal domain of IntS9 which interacts with the C-terminal of IntS11 (responsible for endonuclease activity of INT), a crucial interaction for the role of INT in snRNA 3'-end processing [1,2].

1: Molecular basis for the interaction between Integrator subunits IntS9 and IntS11 and its functional importance. Wu Y, Albrecht TR, Baillat D, Wagner EJ, Tong L; Proc Natl Acad Sci U S A. 2017;114:4394-4399. PMID:28396433

2: Structure of the catalytic core of the Integrator complex. Pfleiderer MM, Galej WP; Mol Cell. 2021;81:1246-1259. PMID:33548203