SIL1 is localized to endoplasmic reticulum (ER). SIL1 is an N-linked glycoprotein with an N-terminal ER targeting sequence, 2 putative N-glycosylation sites, and a C-terminal ER retention signal. SIL1 acts as a nucleotide exchange factor for another unfolded protein response protein. Mutations in SIL1 are linked to Marinesco-Sjogren syndrome.