Syntaxin-1B is a protein in humans that is encoded by STX1B gene. Syntaxin 3, also known as STX3, is a protein which in humans is encoded by the STX3 gene. The protein encoded by this gene is a member of the syntaxin family of cellular receptors for transport vesicles which participate in exocytosis in neutrophils. STX3 has an important role in the growth of neurites and serves as a direct target for omega-6 arachidonic acid. Mutations in Syntaxin 3 cause Microvillus inclusion disease.