SRP-independent targeting protein 3 (SND3, previously known as PHO88) is localized to the endoplasmic reticulum (ER). SND3 works together with SND1 and SND2; these proteins function in parallel with the SRP and GET pathways to target a broad range of substrates to the ER. The SND proteins constitute an alternative targeting route to the ER []. SND3/PHO88 was first identified as a Saccharomyces cerevisiae protein involved in inorganic phosphate transport [].
This family includes SRP-independent targeting protein 2 (SND2) from yeast and transmembrane protein 208 (TMEM208) from mammals. Both are localized to the endoplasmic reticulum (ER) [, ]. SND2 works together with SND1 and SND3 in an alternative targeting route to the ER []. TMEM208 regulates both ER stress and autophagy [].SND2 was previously known as Env10 in Saccharomyces cerevisiae, and its homologue as Mug69 in Schizosaccharomyces pombe. They were identified as proteins involved in vacuolar processing and morphology []and meiosis [], respectively.
