Plays a critical role in several secretory processes, including cuticle secretion and neurotransmitter release, and probably assists in neuronal membrane maturation or the final stages of neuronal differentiation. Essential for embryonic viability and development. Has a role in dauer formation and adult life span. Required for locomotion. Probably by regulating neuronal transmission downstream of lin-3 and receptor lin-23 and phospholipase plc-3 and upstream of innexin unc-7 and egl-4/PKG in ALA neurons, involved in the decrease in pharyngeal pumping during the quiescent state that precedes each larval molt. Interacts with unc-18. Belongs to the syntaxin family.