Surfeit locus protein 4 or Surf4 is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

involved in regulating export of some proteins from the

endoplasmic reticulum The endoplasmic reticulum (ER) is a part of a transportation system of the eukaryote, eukaryotic cell, and has many other important functions such as protein folding. The word endoplasmic means "within the cytoplasm", and reticulum is Latin for ...

to the

golgi bodies The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic Cell (biology), cells. Part of the endomembrane system in the cytoplasm, it protein targeting, packages proteins ...

. Surf4 is involved in trafficking soluble (i.e. non-membrane-bound) proteins, namely

lipoprotein A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, sur ...

s and

PCSK9 Proprotein convertase subtilisin/kexin type 9 (PCSK9) is an enzyme encoded by the ''PCSK9'' gene in humans on chromosome 1. It is the 9th member of the proprotein convertase family of proteins that activate other proteins. Similar genes ( orth ...

. It recognizes cargo proteins via a three-amino-acid sequence near the

N-termini The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the amin ...

. The related protein in

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...

is called Erv29p. This gene is named based on its location in the

surfeit Surfeit is a human gene cluster that consists of a group of very tightly linked genes on chromosome 9 that do not share sequence similarity. Genes in this cluster are numbered 1 through 6: SURF1, SURF2 SURF2 is a protein which in humans is enc ...

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. Eliminating Surf4 in the

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

reduces the amount of

lipid Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...

in the plasma and prevents

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...

in mice.

References

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