RUSC2 is a 1,516 amino acid cytoplasmic protein that is widely expressed, with highest levels in brain and testis. The RUN domain of RUSC2 is required for interaction with Rab 1A, Rab 1B and GM130. It is thought that RUSC2 may possibly function as a connector between endoplasmic reticulum (ER) derived vesicle targets triggered by the Rab 1 GTPases and a signaling pathway regulated by molecules containing SH3 and/or poly-proline regions. RUSC2 also consists of a SH3 domain, suggesting a role in protein-protein interactions. RUSC2 is encoded by a gene located human chromosome 9, which houses over 900 genes and comprises nearly 4% of the human genome. Hereditary hemorrhagic telangiectasia, which is characterized by harmful vascular defects, and Familial dysautonomia, are both associated with chromosome 9. Notably, chromosome 9 encompasses the largest interferon family gene cluster.