OST4
Description
The OST4 (oligosaccharyltransferase complex subunit 4, non-catalytic) is a protein-coding gene located on chromosome 2.
OST4 (Dolichyl-diphosphooligosaccharide—protein glycosyltransferase subunit 4) is a subunit of the oligosaccharyltransferase complex, a protein complex involved in protein glycosylation. OST4 is a very small protein, approximately 30 amino acids long, found in various organisms from fungi to vertebrates. It is an integral membrane protein that helps transfer a pre-assembled sugar molecule (oligosaccharide) onto newly synthesized proteins as they enter the endoplasmic reticulum (ER), a cellular organelle involved in protein processing. OST4 is required for normal levels of oligosaccharyltransferase activity.
OST4 is a subunit of the oligosaccharyltransferase (OST) complex, which plays a crucial role in the initial step of protein N-glycosylation. This process involves transferring a specific glycan (Glc(3)Man(9)GlcNAc(2)) from a lipid carrier to an asparagine residue within a specific sequence (Asn-X-Ser/Thr) in newly synthesized polypeptide chains. This glycosylation occurs during protein synthesis and the OST complex interacts with the Sec61 complex, a channel that facilitates protein movement across the endoplasmic reticulum (ER). All subunits within the OST complex are required for optimal enzyme activity, with OST4 specifically contributing to the stability of the STT3A-containing OST complexes.
OST4 is also known as -.
