Involved in intracellular signal transduction mediated by cytokines and growth factors. Upon IL-2 and GM-CSL stimulation, it plays a role in signaling leading to DNA synthesis and MYC induction. May also play a role in T-cell development. Involved in down-regulation of receptor tyrosine kinase via multivesicular body (MVBs) when complexed with HGS (ESCRT-0 complex). The ESCRT-0 complex binds ubiquitin and acts as sorting machinery that recognizes ubiquitinated receptors and transfers them to further sequential lysosomal sorting/trafficking processes. (Microbial infection) Plays an important role in Dengue virus entry. Component of the ESCRT-0 complex composed of STAM or STAM2 and HGS (PubMed:11687594, PubMed:9407053, PubMed:19278655). Probably part of a complex at least composed of HSG, STAM and EPS15 (PubMed:12551915). Found in a complex with HGS and E3 ligase ITCH and DTX3L (PubMed:24790097). Interacts with E3 ligase DTX3L; the interaction brings together STAM and HSG, promotes their recruitment to early endosomes and decreases STAM and HGS ubiquitination by ITCH (PubMed:24790097). Interacts with STAMBP/AMSH (PubMed:10383417). Interacts with PDGFRB (PubMed:20494825). Interacts with LITAF; the interaction is direct (PubMed:23166352). Identified in a complex with HGS and LITAF (PubMed:23166352). Interacts with HAVCR1 (PubMed:29742433). Ubiquitously expressed. The VHS domain mediates high-avidity binding to Lys63-linked and Lys48-linked polyubiquitinated cargos. Phosphorylated on Tyr-198. Phosphorylated in response to IL2, IL3, IL4, IL7, CSF2/GM-CSF, EGF and PDGFB. Phosphorylated by activated PDGFRB. Ubiquitinated by ITCH. Belongs to the STAM family.