Contributes to the regulation of secretory and vacuolar transport pathways in the post-Golgi network, and to the maintenance of the Golgi apparatus and trans-Golgi network (TGN) morphologies (PubMed:22307646). Together with VTI12, required for membrane fusion (PubMed:15919093). Vesicle trafficking protein that functions in the secretory pathway and mediates liposome fusion; the fusion of phospholipid vesicles containing SYP41 and VTI12 is triggered by YKT61 and YKT62 (PubMed:15919093, PubMed:24021022). Required for extracellular resistance responses to a fungal pathogen (PubMed:22307646). Also involved in the protection of chloroplasts from salicylic acid-dependent biotic stress (PubMed:22307646). Interacts with VTI12 and SYP61 to form a t-SNARE complex and with VPS45 (PubMed:10888666, PubMed:11739776, PubMed:15919093). Interacts with TNO1 (PubMed:21521696). Binds to YKT61 and YKT62 (PubMed:15919093). Core constituent of the SNARE complex required for membrane fusion at the trans-Golgi network (PubMed:15919093). SYP41 is found in a different region of the TGN than SYP42. Mostly expressed in flowers, to a lower extent in leaves and roots, and, at low levels, in stems. Gametophytic lethal in homozygote plants (PubMed:22307646). The double mutant syp41 syp42 have short roots (PubMed:22307646). Plants lacking the three genes SYP41 SYP42 and SYP43 are seedling lethals (PubMed:22307646). Belongs to the syntaxin family.