FABP1 is a human gene coding for the protein product FABP1 (Fatty Acid-Binding Protein 1). It is also frequently known as liver-type fatty acid-binding protein (LFABP).
The fatty acid-binding proteins (FABPs) were initially discovered in 1972 with experiments using 14C labelled oleate to identify the presence of a soluble fatty acid carrier in the enterocyte responsible for intestinal absorption of (LCFAs).[6] Since then, ten members of the FABP family have been identified on the human genome. Nine are well established (FABP1-9) with a recently discovered tenth (FABP12).[3] Each FABP corresponds to particular organs/tissue around the body where they play a role in fatty-acid uptake, transport and metabolism.[6]
Gene location
The human FABP1 gene is located on the short (p) arm of chromosome 2 from base pair 88,122,982 to base pair 88,128,131.[7]
Protein structure
FABP1 has been found to have a unique structure compared to other members of the FABP family, allowing it to bind multiple ligands simultaneously.[8] It also has a larger solvent-accessible core compared to other FABPs allowing more diverse substrate binding.[3] The “portal hypothesis” has been proposed to explain the binding process of FABPs.[3] It has been suggested that fatty acids enter the solvent-accessible area of the protein through a dynamic region consisting of α-helix II and turns between βC-βD and βE-βF loops.[9] The fatty acid is then bound in the protein cavity for transport.[9]
Function
The FABPs are a family of small, highly conserved cytoplasmic proteins involved in the binding of LCFAs. FABP1 is expressed abundantly in the human liver where it accounts for 7-11% of the total cytosolic protein, and can also be found in the intestine, kidney, pancreas stomach and lung.[3][10] FABP1 is unique in the wider range of other hydrophobic ligands it can bind including bilirubin, monoglycerides, bile acids and fatty acyl CoA.[11][12][13][14] It has been proposed that FABP1 plays a significant role in preventing cytotoxicity by binding heme, fatty acids and other molecules that are potentially toxic when unbound.[8]
Mutations
On exon 3 of the human FABP1 gene an Ala to Thr substitution has been identified leading to a T94A missense mutation.[15] Carriers of this particular single nucleotide polymorphism (SNP) exhibit higher baseline plasma-free fatty acid levels, lower BMI and a smaller waist circumference.[15] The T94A mutant has also been associated with metabolic syndrome conditions, cardiovascular disease and T2DM.[15]
Protein expression
Suppression
Studies with mice to determine the effect of suppressing the FABP1 gene have been performed. When provided with high-fat or high-cholesterol based diets those with suppressed FABP1 expression demonstrated a significant impact on metabolic regulation and weight gain.[16][17][18][19]
Increased levels in obesity
A study in Chinese young adults indicates a strong relationship between serum FABP1 levels and lipid profile, body measurements and homeostatic parameters.[5] Increased BMI and insulin resistance in subjects demonstrated higher serum FABP1 with a particular correlation in subjects with central adiposity.[5] This elevation is suggested to occur as a compensatory up-regulation of the protein in an attempt to counter the high metabolic stress associated with obesity. Alternately obesity may in fact lead the human body to develop resistance to the actions of FABP1 leading to the compensatory up-regulation.[5]
Disease marker
Evaluation of increased levels of urinary and serum FABP1 have also shown to be effective markers in the detection of intestinal ischaemia, progressive end-stage renal failure and ischaemic damage caused by renal transplantation or cardiac bypass surgery.[20][21][22]
References
↑Schroeder F, McIntosh AL, Martin GG, Huang H, Landrock D, Chung S, Landrock KK, Dangott LJ, Li S, Kaczocha M, Murphy EJ, Atshaves BP, Kier AB (June 2016). "Fatty Acid Binding Protein-1 (FABP1) and the Human FABP1 T94A Variant: Roles in the Endocannabinoid System and Dyslipidemias". Lipids. 51 (6): 655–76. doi:10.1007/s11745-016-4155-8. PMID27117865.
↑ 9.09.1Sacchettini JC, Gordon JI, Banaszak LJ (July 1989). "Crystal structure of rat intestinal fatty-acid-binding protein. Refinement and analysis of the Escherichia coli-derived protein with bound palmitate". Journal of Molecular Biology. 208 (2): 327–39. doi:10.1016/0022-2836(89)90392-6. PMID2671390.
↑Vergani L, Fanin M, Martinuzzi A, Galassi A, Appi A, Carrozzo R, Rosa M, Angelini C (1990). "Liver fatty acid-binding protein in two cases of human lipid storage". Molecular and Cellular Biochemistry. 98 (1–2): 225–30. doi:10.1007/bf00231388. PMID2266963.
↑Storch J (1993). "Diversity of fatty acid-binding protein structure and function: studies with fluorescent ligands". Molecular and Cellular Biochemistry. 123 (1–2): 45–53. doi:10.1007/BF01076474. PMID8232268.
↑Mishkin S, Turcotte R (April 1974). "The binding of long chain fatty acid CoA to Z, a cytoplasmic protein present in liver and other tissues of the rat". Biochemical and Biophysical Research Communications. 57 (3): 918–26. doi:10.1016/0006-291X(74)90633-0. PMID4827841.
↑ 15.015.115.2Brouillette C, Bossé Y, Pérusse L, Gaudet D, Vohl MC (2004). "Effect of liver fatty acid binding protein (FABP) T94A missense mutation on plasma lipoprotein responsiveness to treatment with fenofibrate". Journal of Human Genetics. 49 (8): 424–32. doi:10.1007/s10038-004-0171-2. PMID15249972.
↑Newberry EP, Xie Y, Kennedy S, Han X, Buhman KK, Luo J, Gross RW, Davidson NO (December 2003). "Decreased hepatic triglyceride accumulation and altered fatty acid uptake in mice with deletion of the liver fatty acid-binding protein gene". Journal of Biological Chemistry. 278 (51): 51664–72. doi:10.1074/jbc.M309377200. PMID14534295.
↑Thuijls G, van Wijck K, Grootjans J, Derikx JP, van Bijnen AA, Heineman E, Dejong CH, Buurman WA, Poeze M (February 2011). "Early diagnosis of intestinal ischemia using urinary and plasma fatty acid binding proteins". Annals of Surgery. 253 (2): 303–8. doi:10.1097/sla.0b013e318207a767. PMID21245670.
↑Kamijo A, Sugaya T, Hikawa A, Kimura K (March 2003). "[Urinary fatty acid binding protein as a new clinical marker for the progression of chronic renal disease]". Rinsho Byori. 51 (3): 219–24. doi:10.1016/j.lab.2003.08.001. PMID12707994.
Further reading
Glatz JF, Börchers T, Spener F, van der Vusse GJ (1995). "Fatty acids in cell signalling: modulation by lipid binding proteins". Prostaglandins, Leukotrienes, and Essential Fatty Acids. 52 (2–3): 121–7. doi:10.1016/0952-3278(95)90010-1. PMID7784447.
Kaikaus RM, Chan WK, Ortiz de Montellano PR, Bass NM (1993). "Mechanisms of regulation of liver fatty acid-binding protein". Molecular and Cellular Biochemistry. 123 (1–2): 93–100. doi:10.1007/BF01076479. PMID8232272.
Londraville RL (June 1996). "Intracellular fatty acid-binding proteins: putting lower vertebrates in perspective". Brazilian Journal of Medical and Biological Research. 29 (6): 707–20. PMID9070383.
Börchers T, Hohoff C, Buhlmann C, Spener F (July 1997). "Heart-type fatty acid binding protein - involvement in growth inhibition and differentiation". Prostaglandins, Leukotrienes, and Essential Fatty Acids. 57 (1): 77–84. doi:10.1016/S0952-3278(97)90496-8. PMID9250612.
Carroll SL, Roth KA, Gordon JI (December 1990). "Liver fatty acid-binding protein: a marker for studying cellular differentiation in gut epithelial neoplasms". Gastroenterology. 99 (6): 1727–35. PMID1699834.
Sweetser DA, Birkenmeier EH, Klisak IJ, Zollman S, Sparkes RS, Mohandas T, Lusis AJ, Gordon JI (November 1987). "The human and rodent intestinal fatty acid binding protein genes. A comparative analysis of their structure, expression, and linkage relationships". Journal of Biological Chemistry. 262 (33): 16060–71. PMID2824476.
Chan L, Wei CF, Li WH, Yang CY, Ratner P, Pownall H, Gotto AM, Smith LC (March 1985). "Human liver fatty acid binding protein cDNA and amino acid sequence. Functional and evolutionary implications". Journal of Biological Chemistry. 260 (5): 2629–32. PMID3838309.
Lowe JB, Boguski MS, Sweetser DA, Elshourbagy NA, Taylor JM, Gordon JI (March 1985). "Human liver fatty acid binding protein. Isolation of a full length cDNA and comparative sequence analyses of orthologous and paralogous proteins". Journal of Biological Chemistry. 260 (6): 3413–7. PMID3838313.
Murphy EJ (August 1998). "L-FABP and I-FABP expression increase NBD-stearate uptake and cytoplasmic diffusion in L cells". American Journal of Physiology. 275 (2 Pt 1): G244–9. PMID9688651.
Wolfrum C, Börchers T, Sacchettini JC, Spener F (February 2000). "Binding of fatty acids and peroxisome proliferators to orthologous fatty acid binding proteins from human, murine, and bovine liver". Biochemistry. 39 (6): 1469–74. doi:10.1021/bi991638u. PMID10684629.
Schroeder F, Atshaves BP, Starodub O, Boedeker AL, Smith RR, Roths JB, Foxworth WB, Kier AB (March 2001). "Expression of liver fatty acid binding protein alters growth and differentiation of embryonic stem cells". Molecular and Cellular Biochemistry. 219 (1–2): 127–38. doi:10.1023/A:1010851130136. PMID11354243.
Zimmerman AW, van Moerkerk HT, Veerkamp JH (September 2001). "Ligand specificity and conformational stability of human fatty acid-binding proteins". The International Journal of Biochemistry & Cell Biology. 33 (9): 865–76. doi:10.1016/S1357-2725(01)00070-X. PMID11461829.
Mésange F, Sebbar M, Capdevielle J, Guillemot JC, Ferrara P, Bayard F, Poirot M, Faye JC (2003). "Identification of two tamoxifen target proteins by photolabeling with 4-(2-morpholinoethoxy)benzophenone". Bioconjugate Chemistry. 13 (4): 766–72. doi:10.1021/bc015588t. PMID12121132.