The proteins in this family are part of a complex of eight ER proteins that transfers core oligosaccharide from dolichol carrier to Asn-X-Ser/Thr motifs [1]. This family includes both OST3 and OST6, each of which contains four predicted transmembrane helices. Disruption of OST3 and OST6 leads to a defect in the assembly of the complex. Hence, the function of these genes seems to be essential for recruiting a fully active complex necessary for efficient N-glycosylation [2]. These proteins are also thought to be novel Mg2+ transporters [3].

1: Functional characterization of Ost3p. Loss of the 34-kD subunit of the Saccharomyces cerevisiae oligosaccharyltransferase results in biased underglycosylation of acceptor substrates. Karaoglu D, Kelleher DJ, Gilmore R; J Cell Biol 1995;130:567-577. PMID:7622558

2: The oligosaccharyltransferase complex from Saccharomyces cerevisiae. Isolation of the OST6 gene, its synthetic interaction with OST3, and analysis of the native complex. Knauer R, Lehle L; J Biol Chem 1999;274:17249-17256. PMID:10358084

3: Identification and characterization of a novel mammalian Mg2+ transporter with channel-like properties. Goytain A, Quamme GA; BMC Genomics. 2005;6:48. PMID:15804357