Involved in intracellular vesicle trafficking. Identified in a complex containing STX6, STX12, VAMP4 and VTI1A (By similarity). Binds EEA1 (PubMed:10506127). Interacts with VPS45A and GOPC (By similarity). Interacts with MARCHF2; the interaction promotes MARCHF2-mediated ubiquitination and degradation of CFTR (PubMed:15689499). Interacts with MARCHF3 (PubMed:16428329). Interacts with UHRF1BP1L (via C-terminal coiled-coil domain) (PubMed:20163565). Interacts with BAIAP3; this interaction is increased in the presence of calcium (By similarity). Widely expressed, with relatively higher expression in brain, lung and kidney. Belongs to the syntaxin family.