SNAREs, soluble N-ethylmaleimide-sensitive factor-attachment protein receptors, are essential proteins for fusion of cellular membranes. SNAREs localized on opposing membranes assemble to form a trans-SNARE complex, an extended, parallel four alpha-helical bundle that drives membrane fusion. STX17 is a SNARE of the autophagosome involved in autophagy through the direct control of autophagosome membrane fusion with the lysosome membrane. May also play a role in the early secretory pathway where it may maintain the architecture of the endoplasmic reticulum-Golgi intermediate compartment/ERGIC and Golgi and/or regulate transport between the endoplasmic reticulum, the ERGIC and the Golgi (By similarity). Forms a SNARE complex composed of VAMP8, SNAP29 and STX17 involved in fusion of autophagosome with lysosome (By similarity). May interact with VAMP7 (By similarity). May interact with VTI1B (By similarity). Probably interacts with BET1, SCFD1 and SEC22B (PubMed:10930465). Interacts with PTPN2 and ABL1; involved in STX17 phosphorylation (PubMed:23006999). Interacts with COPB1 (PubMed:21545355). Interacts with TMED9 and TMED10; the interaction is direct (PubMed:21545355). Interacts with RUBCNL/PACER; promoting targeting of RUBCNL/PACER to autophagosome (By similarity). Interacts with VAMP8, SNAP29, VPS39 and VPS41; these interactions are increased in the absence of TMEM39A (By similarity). Has a hairpin-like insertion into membranes. Localized into endoplasmic reticulum membranes, it also localizes to the completed autophagosome membrane upon cell starvation (By similarity). Detected in all tissues examined with higher expression in steroidogenic tissues including testis and adrenal gland (at protein level). Highly expressed in liver and testis. Also found in brain, heart, kidney, lung, placenta, skeletal muscle and spleen. Phosphorylated at Tyr-156 probably by ABL1. Dephosphorylation by PTPN2; regulates exit from the endoplasmic reticulum. Belongs to the syntaxin family.