Acts upstream of or within cellular response to estrogen stimulus. Predicted to be located in endoplasmic reticulum membrane. Predicted to be active in endomembrane system. Is expressed in several structures, including axis; endocrine system; hatching gland; notochord; and polster. Human ortholog(s) of this gene implicated in congenital disorder of glycosylation Iy. Orthologous to human SSR4 (signal sequence receptor subunit 4).