Abetalipoproteinemia is a disorder characterized by abnormal absorption of fat and fat-soluble vitamins from food. It is caused by a mutation in microsomal triglyceride transfer protein resulting in deficiencies in the apolipoproteins B-48 and B-100, which are used in the synthesis and exportation of chylomicrons and VLDL respectively. It is not to be confused with familial dysbetalipoproteinemia.
Mediated transport refers to transport mediated by a membrane transport protein. Substances in the human body may be hydrophobic, electrophilic, contain a positively or negatively charge, or have another property. As such there are times when those substances may not be able to pass over the cell membrane using protein-independent movement. The cell membrane is imbedded with many membrane transport proteins that allow such molecules to travel in and out of the cell. There are three types of mediated transporters: uniport, symport, and antiport. Things that can be transported are nutrients, ions, glucose, etc, all depending on the needs of the cell. One example of a uniport mediated transport protein is GLUT1. GLUT1 is a transmembrane protein, which means it spans the entire width of the cell membrane, connecting the extracellular and intracellular region. It is a uniport system because it specifically transports glucose in only one direction, down its concentration gradient across the cell membrane.
In cell biology, microsomes are heterogeneous vesicle-like artifacts re-formed from pieces of the endoplasmic reticulum (ER) when eukaryotic cells are broken-up in the laboratory; microsomes are not present in healthy, living cells.
The low-density lipoprotein receptor (LDL-R) is a mosaic protein of 839 amino acids that mediates the endocytosis of cholesterol-rich low-density lipoprotein (LDL). It is a cell-surface receptor that recognizes apolipoprotein B100 (ApoB100), which is embedded in the outer phospholipid layer of very low-density lipoprotein (VLDL), their remnants—i.e. intermediate-density lipoprotein (IDL), and LDL particles. The receptor also recognizes apolipoprotein E (ApoE) which is found in chylomicron remnants and IDL. In humans, the LDL receptor protein is encoded by the LDLR gene on chromosome 19. It belongs to the low density lipoprotein receptor gene family. It is most significantly expressed in bronchial epithelial cells and adrenal gland and cortex tissue.
Apolipoprotein B (ApoB) is a protein that in humans is encoded by the APOB gene. It is commonly used to detect risk of atherosclerotic cardiovascular disease.
Vitellogenin is a precursor of egg yolk that transports protein and some lipid from the liver through the blood to the growing oocytes where it becomes part of the yolk. Normally, it is only found in the blood or hemolymph of females, and can therefore be used as a biomarker in vertebrates of exposure to environmental estrogens which stimulate elevated levels in males as well as females. "Vitellogenin" is a synonymous term for the gene and the expressed protein. The protein product is classified as a glycolipoprotein, having properties of a sugar, fat and protein. It belongs to a family of several lipid transport proteins.
Apolipoprotein C-II, or apolipoprotein C2 is a protein that in humans is encoded by the APOC2 gene.
Sterol regulatory element-binding protein cleavage-activating protein, also known as SREBP cleavage-activating protein or SCAP, is a protein that in humans is encoded by the SCAP gene.
Phospholipid transfer protein is a protein that in humans is encoded by the PLTP gene.
Protein disulfide-isomerase, also known as the beta-subunit of prolyl 4-hydroxylase (P4HB), is an enzyme that in humans encoded by the P4HB gene. The human P4HB gene is localized in chromosome 17q25. Unlike other prolyl 4-hydroxylase family proteins, this protein is multifunctional and acts as an oxidoreductase for disulfide formation, breakage, and isomerization. The activity of P4HB is tightly regulated. Both dimer dissociation and substrate binding are likely to enhance its enzymatic activity during the catalysis process.
Glucose-6-phosphatase, catalytic subunit is an enzyme that in humans is encoded by the G6PC gene.
Apolipoprotein B mRNA editing enzyme, catalytic polypeptide 1 also known as C->U-editing enzyme APOBEC-1 is a protein that in humans is encoded by the APOBEC1 gene.
GPI transamidase component PIG-T is an enzyme that in humans is encoded by the PIGT gene.
Protein SEC13 homolog is a protein that in humans is encoded by the SEC13 gene.
Arylacetamide deacetylase is an enzyme that in humans is encoded by the AADAC gene.
GPI transamidase component PIG-S is an enzyme that in humans is encoded by the PIGS gene. This gene encodes a protein that is involved in GPI-anchor biosynthesis.
Apolipoprotein F is a protein that in humans is encoded for by the APOF gene. The product of this gene is one of the minor apolipoproteins found in plasma. This protein forms complexes with lipoproteins and may be involved in transport and/or esterification of cholesterol.
Mitochondrially encoded tRNA proline also known as MT-TP is a transfer RNA that in humans is encoded by the mitochondrial MT-TP gene.
Apolipoprotein O also known as protein FAM121B is a protein that in humans is encoded by the APOO gene. APOO is a member of the apolipoprotein family.
Protein disulfide isomerase family A member 2 is a protein that in humans is encoded by the PDIA2 gene.
