The protein encoded by this gene is a member of the apolipoprotein C family. This gene is expressed primarily in the liver, and it is activated when monocytes differentiate into macrophages. A pseudogene of this gene is located 4 kb downstream in the same orientation, on the same chromosome. This gene is mapped to chromosome 19, where it resides within an apolipoprotein gene cluster. Alternatively spliced transcript variants have been found for this gene, but the biological validity of some variants has not been determined.
Apolipoprotein C1 has a length of 57 amino acids normally found in plasma and responsible for the activation of esterified lechitin cholesterol with an important role in the exchange of esterified cholesterol between lipoproteins and in removal of cholesterol from tissues. Its main function is inhibition of CETP, probably by altering the electric charge of HDL molecules.
During fasting (like other apolipoprotein C), it is found primarily within HDL, while after a meal it is found on the surface of other lipoproteins. When proteins rich in triglycerides like chylomicrons and VLDL are broken down, this apoprotein is transferred again to HDL. It is one of the most positively charged proteins in the human body.
^Tata F, Henry I, Markham AF, Wallis SC, Weil D, Grzeschik KH, Junien C, Williamson R, Humphries SE (1985). "Isolation and characterisation of a cDNA clone for human apolipoprotein CI and assignment of the gene to chromosome 19". Hum. Genet.69 (4): 345–9. doi:10.1007/BF00291654. PMID2985493.
^Smit M, van der Kooij-Meijs E, Frants RR, Havekes L, Klasen EC (January 1988). "Apolipoprotein gene cluster on chromosome 19. Definite localization of the APOC2 gene and the polymorphic Hpa I site associated with type III hyperlipoproteinemia". Hum. Genet.78 (1): 90–3. doi:10.1007/BF00291243. PMID2892779.
Shulman RS, Herbert PN, Wehrly K, Fredrickson DS (1975). "Thf complete amino acid sequence of C-I (apoLp-Ser), an apolipoprotein from human very low density lipoproteins". J. Biol. Chem.250 (1): 182–90. PMID166984.
Lauer SJ, Walker D, Elshourbagy NA, et al. (1988). "Two copies of the human apolipoprotein C-I gene are linked closely to the apolipoprotein E gene". J. Biol. Chem.263 (15): 7277–86. PMID2835369.
Smit M, van der Kooij-Meijs E, Woudt LP, et al. (1988). "Exact localization of the familial dysbetalipoproteinemia associated HpaI restriction site in the promoter region of the APOC1 gene". Biochem. Biophys. Res. Commun.152 (3): 1282–8. doi:10.1016/S0006-291X(88)80424-8. PMID2897845.
Davison PJ, Norton P, Wallis SC, et al. (1986). "There are two gene sequences for human apolipoprotein CI (apo CI) on chromosome 19, one of which is 4 kb from the gene for apo E". Biochem. Biophys. Res. Commun.136 (3): 876–84. doi:10.1016/0006-291X(86)90414-6. PMID3013172.
Myklebost O, Rogne S (1986). "The gene for human apolipoprotein CI is located 4.3 kilobases away from the apolipoprotein E gene on chromosome 19". Hum. Genet.73 (4): 286–9. doi:10.1007/BF00279087. PMID3017837.
Jackson RL, Sparrow JT, Baker HN, et al. (1974). "The primary structure of apolopoprotein-serine". J. Biol. Chem.249 (16): 5308–13. PMID4369340.
Servillo L, Brewer HB, Osborne JC (1981). "Evaluation of the mixed interaction between apolipoproteins A-II and C-I equilibrium sedimentation". Biophys. Chem.13 (1): 29–38. doi:10.1016/0301-4622(81)80022-1. PMID6789904.
Curry MD, McConathy WJ, Fesmire JD, Alaupovic P (1981). "Quantitative determination of apolipoproteins C-I and C-II in human plasma by separate electroimmunoassays". Clin. Chem.27 (4): 543–8. PMID7471419.
Rozek A, Buchko GW, Cushley RJ (1995). "Conformation of two peptides corresponding to human apolipoprotein C-I residues 7-24 and 35-53 in the presence of sodium dodecyl sulfate by CD and NMR spectroscopy". Biochemistry34 (22): 7401–8. doi:10.1021/bi00022a013. PMID7779782.
Trask B, Fertitta A, Christensen M, et al. (1993). "Fluorescence in situ hybridization mapping of human chromosome 19: cytogenetic band location of 540 cosmids and 70 genes or DNA markers". Genomics15 (1): 133–45. doi:10.1006/geno.1993.1021. PMID8432525.
Kamino K, Yoshiiwa A, Nishiwaki Y, et al. (1996). "Genetic association study between senile dementia of Alzheimer's type and APOE/C1/C2 gene cluster". Gerontology. 42 Suppl 1: 12–9. doi:10.1159/000213820. PMID8804993.
Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, et al. (1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library". Gene200 (1–2): 149–56. doi:10.1016/S0378-1119(97)00411-3. PMID9373149.
Halushka MK, Fan JB, Bentley K, et al. (1999). "Patterns of single-nucleotide polymorphisms in candidate genes for blood-pressure homeostasis". Nat. Genet.22 (3): 239–47. doi:10.1038/10297. PMID10391210.
Gautier T, Masson D, de Barros JP, et al. (2001). "Human apolipoprotein C-I accounts for the ability of plasma high density lipoproteins to inhibit the cholesteryl ester transfer protein activity". J. Biol. Chem.275 (48): 37504–9. doi:10.1074/jbc.M007210200. PMID10978346.