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Pathway Description
Bloch Pathway (Cholesterol Biosynthesis)
Homo sapiens
Metabolic Pathway
Created: 2019-01-17
Last Updated: 2023-10-28
The Bloch pathway, named after Konrad Bloch, is the pathway following the mevalonate pathway occurring within the cell to complete cholesterol biosynthesis. Cholesterol is a necessary metabolite that helps create many essential hormones within the human body. This pathway, combined with the mevalonate pathway is one of two ways to biosynthesize cholesterol; the Kandutsch-Russell pathway is an alternative pathway that uses different compounds than the Bloch Pathway beginning after lanosterol. The first three reactions occur in the endoplasmic reticulum. Lanosterol, a compound created through the mevalonate pathway, binds with the enzyme lanosterol 14-alpha demethylase to become 4,4-dimethyl-14a-hydroxymethyl-5a-cholesta-8,24-dien-3b-ol. Moving to the next reaction, 4,4-dimethyl-14a-hydroxymethyl-5a-cholesta-8,24-dien-3b-ol utilizes the enzyme lanosterol 14-alpha demethylase to create 4,4-dimethyl-14α-formyl-5α-cholesta-8,24-dien-3β-ol. Lanosterol 14-alpha demethylase is used one last time in this pathway, converting 4,4-dimethyl-14α-formyl-5α-cholesta-8,24-dien-3β-ol into 4,4-dimethyl-5a-cholesta-8,14,24-trien-3b-ol. Entering the inner nuclear membrane, 4,4-dimethyl-5a-cholesta-8,14,24-trien-3b-ol is catalyzed by a lamin B receptor to create 4,4-dimethyl-5a-cholesta-8,24-dien-3-b-ol. Entering the endoplasmic reticulum membrane, 4,4-dimethyl-5a-cholesta-8,24-dien-3-b-ol, with the help of methyl monooxygenase 1 is converted to 4a-hydroxymethyl-4b-methyl-5a-cholesta-8,24-dien-3b-ol. The enzyme methyl monooxygenase 1 uses 4a-hydroxymethyl-4b-methyl-5a-cholesta-8,24-dien-3b-ol to produce 4a-formyl-4b-methyl-5a-cholesta-8,24-dien-3b-ol. This reaction is repeated once more, using 4a-formyl-4b-methyl-5a-cholesta-8,24-dien-3b-ol and methyl monooxygenase 1 to create 4a-carboxy-4b-methyl-5a-cholesta-8,24-dien-3b-ol. Briefly entering the endoplasmic reticulum, 4a-carboxy-4b-methyl-5a-cholesta-8,24-dien-3b-ol then uses sterol-4-alpha-carboxylate-3-dehyrogenase to catalyze into 3-keto-4-methylzymosterol. Back in the endoplasmic reticulum membrane, where the pathway will continue on for the remaining reactions, 3-keto-4-methylzymosterol combines with 3-keto-steroid reductase to create 4a-methylzymosterol. 4a-Methylzymosterol joins the enzyme methylsterol monooxgenase 1 to result in 4a-hydroxymethyl-5a-cholesta-8,24-dien-3b-ol. 4a-Hydroxymethyl-5a-cholesta-8,24-dien-3b-ol uses methylsterol monooxygenase 1 to convert to 4a-formyl-5a-cholesta-8,24-dien-3b-ol. 4a-Formyl-5a-cholesta-8,24-dien-3b-ol proceeds to use the same enzyme used in the previous reaction: methylsterol monooxygenase 1, to catalyze into 4a-carboxy-5a-cholesta-8,24-dien-3b-ol. Sterol-4-alpha-carboxylate-3-dehydrogenase is used alongside 4a-carboxy-5a-cholesta-8,24-dien-3b-ol to produce 5a-cholesta-8,24-dien-3-one (also known as zymosterone). Zymosterone (5a-cholesta-8,24-dien-3-one) teams up with 3-keto-steroid reductase to create zymosterol. Zymosterol proceeds to use the enzyme 3-beta-hydroxysteroid-delta(8),delta(7)-isomerase to catalyze into 5a-cholesta-7,24-dien-3b-ol. The compound 5a-cholesta-7,24-dien-3b-ol then joins lathosterol oxidase to convert to 7-dehydrodesmosterol. 7-Dehydrodesmosterol and the enzyme 7-dehydrocholesterol reductase come together to create desmosterol. This brings the pathway to the final reaction, where desmosterol combines with delta(24)-sterol reductase to finally convert to cholesterol.
References
Bloch Pathway (Cholesterol Biosynthesis) References
Sharpe LJ, Brown AJ: Controlling cholesterol synthesis beyond 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). J Biol Chem. 2013 Jun 28;288(26):18707-15. doi: 10.1074/jbc.R113.479808. Epub 2013 May 21.
Pubmed: 23696639
Zerenturk EJ, Sharpe LJ, Ikonen E, Brown AJ: Desmosterol and DHCR24: unexpected new directions for a terminal step in cholesterol synthesis. Prog Lipid Res. 2013 Oct;52(4):666-80. doi: 10.1016/j.plipres.2013.09.002. Epub 2013 Oct 2.
Pubmed: 24095826
Stromstedt M, Rozman D, Waterman MR: The ubiquitously expressed human CYP51 encodes lanosterol 14 alpha-demethylase, a cytochrome P450 whose expression is regulated by oxysterols. Arch Biochem Biophys. 1996 May 1;329(1):73-81. doi: 10.1006/abbi.1996.0193.
Pubmed: 8619637
Aoyama Y, Noshiro M, Gotoh O, Imaoka S, Funae Y, Kurosawa N, Horiuchi T, Yoshida Y: Sterol 14-demethylase P450 (P45014DM*) is one of the most ancient and conserved P450 species. J Biochem. 1996 May;119(5):926-33. doi: 10.1093/oxfordjournals.jbchem.a021331.
Pubmed: 8797093
Rozman D, Stromstedt M, Waterman MR: The three human cytochrome P450 lanosterol 14 alpha-demethylase (CYP51) genes reside on chromosomes 3, 7, and 13: structure of the two retrotransposed pseudogenes, association with a line-1 element, and evolution of the human CYP51 family. Arch Biochem Biophys. 1996 Sep 15;333(2):466-74. doi: 10.1006/abbi.1996.0416.
Pubmed: 8809088
Ye Q, Worman HJ: Primary structure analysis and lamin B and DNA binding of human LBR, an integral protein of the nuclear envelope inner membrane. J Biol Chem. 1994 Apr 15;269(15):11306-11.
Pubmed: 8157662
Papoutsopoulou S, Nikolakaki E, Giannakouros T: SRPK1 and LBR protein kinases show identical substrate specificities. Biochem Biophys Res Commun. 1999 Feb 24;255(3):602-7. doi: 10.1006/bbrc.1999.0249.
Pubmed: 10049757
Duband-Goulet I, Courvalin JC: Inner nuclear membrane protein LBR preferentially interacts with DNA secondary structures and nucleosomal linker. Biochemistry. 2000 May 30;39(21):6483-8. doi: 10.1021/bi992908b.
Pubmed: 10828963
Li L, Kaplan J: Characterization of yeast methyl sterol oxidase (ERG25) and identification of a human homologue. J Biol Chem. 1996 Jul 12;271(28):16927-33. doi: 10.1074/jbc.271.28.16927.
Pubmed: 8663358
Ota T, Suzuki Y, Nishikawa T, Otsuki T, Sugiyama T, Irie R, Wakamatsu A, Hayashi K, Sato H, Nagai K, Kimura K, Makita H, Sekine M, Obayashi M, Nishi T, Shibahara T, Tanaka T, Ishii S, Yamamoto J, Saito K, Kawai Y, Isono Y, Nakamura Y, Nagahari K, Murakami K, Yasuda T, Iwayanagi T, Wagatsuma M, Shiratori A, Sudo H, Hosoiri T, Kaku Y, Kodaira H, Kondo H, Sugawara M, Takahashi M, Kanda K, Yokoi T, Furuya T, Kikkawa E, Omura Y, Abe K, Kamihara K, Katsuta N, Sato K, Tanikawa M, Yamazaki M, Ninomiya K, Ishibashi T, Yamashita H, Murakawa K, Fujimori K, Tanai H, Kimata M, Watanabe M, Hiraoka S, Chiba Y, Ishida S, Ono Y, Takiguchi S, Watanabe S, Yosida M, Hotuta T, Kusano J, Kanehori K, Takahashi-Fujii A, Hara H, Tanase TO, Nomura Y, Togiya S, Komai F, Hara R, Takeuchi K, Arita M, Imose N, Musashino K, Yuuki H, Oshima A, Sasaki N, Aotsuka S, Yoshikawa Y, Matsunawa H, Ichihara T, Shiohata N, Sano S, Moriya S, Momiyama H, Satoh N, Takami S, Terashima Y, Suzuki O, Nakagawa S, Senoh A, Mizoguchi H, Goto Y, Shimizu F, Wakebe H, Hishigaki H, Watanabe T, Sugiyama A, Takemoto M, Kawakami B, Yamazaki M, Watanabe K, Kumagai A, Itakura S, Fukuzumi Y, Fujimori Y, Komiyama M, Tashiro H, Tanigami A, Fujiwara T, Ono T, Yamada K, Fujii Y, Ozaki K, Hirao M, Ohmori Y, Kawabata A, Hikiji T, Kobatake N, Inagaki H, Ikema Y, Okamoto S, Okitani R, Kawakami T, Noguchi S, Itoh T, Shigeta K, Senba T, Matsumura K, Nakajima Y, Mizuno T, Morinaga M, Sasaki M, Togashi T, Oyama M, Hata H, Watanabe M, Komatsu T, Mizushima-Sugano J, Satoh T, Shirai Y, Takahashi Y, Nakagawa K, Okumura K, Nagase T, Nomura N, Kikuchi H, Masuho Y, Yamashita R, Nakai K, Yada T, Nakamura Y, Ohara O, Isogai T, Sugano S: Complete sequencing and characterization of 21,243 full-length human cDNAs. Nat Genet. 2004 Jan;36(1):40-5. doi: 10.1038/ng1285. Epub 2003 Dec 21.
Pubmed: 14702039
Hillier LW, Graves TA, Fulton RS, Fulton LA, Pepin KH, Minx P, Wagner-McPherson C, Layman D, Wylie K, Sekhon M, Becker MC, Fewell GA, Delehaunty KD, Miner TL, Nash WE, Kremitzki C, Oddy L, Du H, Sun H, Bradshaw-Cordum H, Ali J, Carter J, Cordes M, Harris A, Isak A, van Brunt A, Nguyen C, Du F, Courtney L, Kalicki J, Ozersky P, Abbott S, Armstrong J, Belter EA, Caruso L, Cedroni M, Cotton M, Davidson T, Desai A, Elliott G, Erb T, Fronick C, Gaige T, Haakenson W, Haglund K, Holmes A, Harkins R, Kim K, Kruchowski SS, Strong CM, Grewal N, Goyea E, Hou S, Levy A, Martinka S, Mead K, McLellan MD, Meyer R, Randall-Maher J, Tomlinson C, Dauphin-Kohlberg S, Kozlowicz-Reilly A, Shah N, Swearengen-Shahid S, Snider J, Strong JT, Thompson J, Yoakum M, Leonard S, Pearman C, Trani L, Radionenko M, Waligorski JE, Wang C, Rock SM, Tin-Wollam AM, Maupin R, Latreille P, Wendl MC, Yang SP, Pohl C, Wallis JW, Spieth J, Bieri TA, Berkowicz N, Nelson JO, Osborne J, Ding L, Meyer R, Sabo A, Shotland Y, Sinha P, Wohldmann PE, Cook LL, Hickenbotham MT, Eldred J, Williams D, Jones TA, She X, Ciccarelli FD, Izaurralde E, Taylor J, Schmutz J, Myers RM, Cox DR, Huang X, McPherson JD, Mardis ER, Clifton SW, Warren WC, Chinwalla AT, Eddy SR, Marra MA, Ovcharenko I, Furey TS, Miller W, Eichler EE, Bork P, Suyama M, Torrents D, Waterston RH, Wilson RK: Generation and annotation of the DNA sequences of human chromosomes 2 and 4. Nature. 2005 Apr 7;434(7034):724-31. doi: 10.1038/nature03466.
Pubmed: 15815621
McLarren KW, Severson TM, du Souich C, Stockton DW, Kratz LE, Cunningham D, Hendson G, Morin RD, Wu D, Paul JE, An J, Nelson TN, Chou A, DeBarber AE, Merkens LS, Michaud JL, Waters PJ, Yin J, McGillivray B, Demos M, Rouleau GA, Grzeschik KH, Smith R, Tarpey PS, Shears D, Schwartz CE, Gecz J, Stratton MR, Arbour L, Hurlburt J, Van Allen MI, Herman GE, Zhao Y, Moore R, Kelley RI, Jones SJ, Steiner RD, Raymond FL, Marra MA, Boerkoel CF: Hypomorphic temperature-sensitive alleles of NSDHL cause CK syndrome. Am J Hum Genet. 2010 Dec 10;87(6):905-14. doi: 10.1016/j.ajhg.2010.11.004.
Pubmed: 21129721
Mallon AM, Platzer M, Bate R, Gloeckner G, Botcherby MR, Nordsiek G, Strivens MA, Kioschis P, Dangel A, Cunningham D, Straw RN, Weston P, Gilbert M, Fernando S, Goodall K, Hunter G, Greystrong JS, Clarke D, Kimberley C, Goerdes M, Blechschmidt K, Rump A, Hinzmann B, Mundy CR, Miller W, Poustka A, Herman GE, Rhodes M, Denny P, Rosenthal A, Brown SD: Comparative genome sequence analysis of the Bpa/Str region in mouse and Man. Genome Res. 2000 Jun;10(6):758-75. doi: 10.1101/gr.10.6.758.
Pubmed: 10854409
Deloukas P, Earthrowl ME, Grafham DV, Rubenfield M, French L, Steward CA, Sims SK, Jones MC, Searle S, Scott C, Howe K, Hunt SE, Andrews TD, Gilbert JG, Swarbreck D, Ashurst JL, Taylor A, Battles J, Bird CP, Ainscough R, Almeida JP, Ashwell RI, Ambrose KD, Babbage AK, Bagguley CL, Bailey J, Banerjee R, Bates K, Beasley H, Bray-Allen S, Brown AJ, Brown JY, Burford DC, Burrill W, Burton J, Cahill P, Camire D, Carter NP, Chapman JC, Clark SY, Clarke G, Clee CM, Clegg S, Corby N, Coulson A, Dhami P, Dutta I, Dunn M, Faulkner L, Frankish A, Frankland JA, Garner P, Garnett J, Gribble S, Griffiths C, Grocock R, Gustafson E, Hammond S, Harley JL, Hart E, Heath PD, Ho TP, Hopkins B, Horne J, Howden PJ, Huckle E, Hynds C, Johnson C, Johnson D, Kana A, Kay M, Kimberley AM, Kershaw JK, Kokkinaki M, Laird GK, Lawlor S, Lee HM, Leongamornlert DA, Laird G, Lloyd C, Lloyd DM, Loveland J, Lovell J, McLaren S, McLay KE, McMurray A, Mashreghi-Mohammadi M, Matthews L, Milne S, Nickerson T, Nguyen M, Overton-Larty E, Palmer SA, Pearce AV, Peck AI, Pelan S, Phillimore B, Porter K, Rice CM, Rogosin A, Ross MT, Sarafidou T, Sehra HK, Shownkeen R, Skuce CD, Smith M, Standring L, Sycamore N, Tester J, Thorpe A, Torcasso W, Tracey A, Tromans A, Tsolas J, Wall M, Walsh J, Wang H, Weinstock K, West AP, Willey DL, Whitehead SL, Wilming L, Wray PW, Young L, Chen Y, Lovering RC, Moschonas NK, Siebert R, Fechtel K, Bentley D, Durbin R, Hubbard T, Doucette-Stamm L, Beck S, Smith DR, Rogers J: The DNA sequence and comparative analysis of human chromosome 10. Nature. 2004 May 27;429(6990):375-81. doi: 10.1038/nature02462.
Pubmed: 15164054
Krazeisen A, Breitling R, Imai K, Fritz S, Moller G, Adamski J: Determination of cDNA, gene structure and chromosomal localization of the novel human 17beta-hydroxysteroid dehydrogenase type 7(1). FEBS Lett. 1999 Oct 29;460(2):373-9. doi: 10.1016/s0014-5793(99)01366-6.
Pubmed: 10544267
Torn S, Nokelainen P, Kurkela R, Pulkka A, Menjivar M, Ghosh S, Coca-Prados M, Peltoketo H, Isomaa V, Vihko P: Production, purification, and functional analysis of recombinant human and mouse 17beta-hydroxysteroid dehydrogenase type 7. Biochem Biophys Res Commun. 2003 May 23;305(1):37-45. doi: 10.1016/s0006-291x(03)00694-6.
Pubmed: 12732193
Clark HF, Gurney AL, Abaya E, Baker K, Baldwin D, Brush J, Chen J, Chow B, Chui C, Crowley C, Currell B, Deuel B, Dowd P, Eaton D, Foster J, Grimaldi C, Gu Q, Hass PE, Heldens S, Huang A, Kim HS, Klimowski L, Jin Y, Johnson S, Lee J, Lewis L, Liao D, Mark M, Robbie E, Sanchez C, Schoenfeld J, Seshagiri S, Simmons L, Singh J, Smith V, Stinson J, Vagts A, Vandlen R, Watanabe C, Wieand D, Woods K, Xie MH, Yansura D, Yi S, Yu G, Yuan J, Zhang M, Zhang Z, Goddard A, Wood WI, Godowski P, Gray A: The secreted protein discovery initiative (SPDI), a large-scale effort to identify novel human secreted and transmembrane proteins: a bioinformatics assessment. Genome Res. 2003 Oct;13(10):2265-70. doi: 10.1101/gr.1293003. Epub 2003 Sep 15.
Pubmed: 12975309
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