Apolipoprotein D (ApoD) is a protein that in humans is encoded by the APOD gene.[5][6][7] Unlike other lipoproteins, which are mainly produced in the liver, apolipoprotein D is mainly produced in the brain and testes.[8] It is a 29 kDa glycoprotein discovered in 1963 as a component of the high-density lipoprotein (HDL) fraction of human plasma.[9][10] It is the major component of human mammary cyst fluid. The human gene encoding it was cloned in 1986 and the deduced protein sequence revealed that ApoD is a member of the lipocalin family, small hydrophobic molecule transporters.[6] ApoD is 169 amino acids long, including a secretion peptide signal of 20 amino acids. It contains two glycosylation sites (aspargines 45 and 78) and the molecular weight of the mature protein varies from 20 to 32 kDa (see figure 1).
The resolved tertiary structure shows that ApoD is composed of 8 anti-parallel β-strands forming a hydrophobic cavity capable of receiving different ligands.[11][12] ApoD also contains 5 cysteine residues, 4 of which are involved in intra-molecular disulfide bonds.
- ^ a b c GRCh38: Ensembl release 89: ENSG00000189058 – Ensembl, May 2017
- ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000022548 – Ensembl, May 2017
- ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ Drayna DT, McLean JW, Wion KL, Trent JM, Drabkin HA, Lawn RM (June 1987). "Human apolipoprotein D gene: gene sequence, chromosome localization, and homology to the alpha 2u-globulin superfamily". DNA. 6 (3): 199–204. doi:10.1089/dna.1987.6.199. PMID 2439269.
- ^ a b Drayna D, Fielding C, McLean J, Baer B, Castro G, Chen E, et al. (December 1986). "Cloning and expression of human apolipoprotein D cDNA". The Journal of Biological Chemistry. 261 (35): 16535–9. doi:10.1016/S0021-9258(18)66599-8. PMID 3453108.
- ^ "Entrez Gene: APOD apolipoprotein D".
- ^ Muffat J, Walker DW (January 2010). "Apolipoprotein D: an overview of its role in aging and age-related diseases". Cell Cycle. 9 (2): 269–73. doi:10.4161/cc.9.2.10433. PMC 3691099. PMID 20023409.
- ^ Ayrault Jarrier M, Levy G, Polonovski J (August 1963). "[Study of Human Serum Alpha-Lipoproteins by Immunoelectrophoresis]". Bulletin de la Société de Chimie Biologique. 45: 703–13. PMID 14051455.
- ^ McConathy WJ, Alaupovic P (February 1976). "Studies on the isolation and partial characterization of apolipoprotein D and lipoprotein D of human plasma". Biochemistry. 15 (3): 515–20. doi:10.1021/bi00648a010. PMID 56198.
- ^ Peitsch MC, Boguski MS (February 1990). "Is apolipoprotein D a mammalian bilin-binding protein?". The New Biologist. 2 (2): 197–206. PMID 2083249.
- ^ Eichinger A, Nasreen A, Kim HJ, Skerra A (October 2007). "Structural insight into the dual ligand specificity and mode of high density lipoprotein association of apolipoprotein D". The Journal of Biological Chemistry. 282 (42): 31068–75. doi:10.1074/jbc.M703552200. PMID 17699160. S2CID 9647650.