8.A.91.1.6
Syntaxin 3 (Stx3) of 289 aas with a C-terminal transmembrane anchor domain, is a  SNARE protein that is required for its membrane fusion activity.  Stx3 also functions as a nuclear regulator of gene expression. Alternative splicing creates a soluble isoform (Stx3S), lacking the transmembrane anchor which binds to the nuclear import factor RanBP5 (RAN-binding protein 5), targets to the nucleus, and interacts physically and functionally with several transcription factors (Giovannone et al. 2018). Mutations can cause microvillus inclusion disease (Julia et al. 2019).