SURF4

Surfeit locus protein 4 or Surf4 is a protein involved in regulating export of some proteins from the endoplasmic reticulum to the golgi bodies.^[4][5] Surf4 is involved in trafficking soluble (i.e. non-membrane-bound) proteins, namely lipoproteins and PCSK9.^[4] It recognizes cargo proteins via a three-amino-acid sequence near the N-termini.^[4] The related protein in yeast is called Erv29p.^[5]

This gene is named based on its location in the surfeit gene cluster, composed of six housekeeping genes that do not share sequence similarity. The encoded protein is a conserved integral membrane protein containing multiple putative transmembrane regions. Surf4's yeast homolog is directly required for packaging glycosylated pro-alpha-factor into COPII vesicles.^[6]

Eliminating Surf4 in the liver reduces the amount of lipid in the plasma and prevents atherosclerosis in mice.^[4]