Phosphorylation, Subcellular Localization, and Membrane Orientation of the Alzheimer's Disease-associated Presenilins

Presenilins 1 and 2 are unglycosylated proteins with apparent molecular mass of 45 and 50 kDa, respectively, in transfected COS-1 and Chinese hamster ovary cells. They colocalize with proteins from the endoplasmic reticulum and the Golgi apparatus in transfected and untransfected cells. In COS-1 cells low amounts of intact endogeneous presenilin 1 migrating at 45 kDa are detected together with relative larger amounts of presenilin 1 fragments migrating between 18 and 30 kDa. The presenilins have a strong tendency to form aggregates (mass of 100-250 kDa) in SDS-polyacrylamide gel electrophoresis, which can be partially resolved when denatured by SDS at 37°C instead of 95°C. Sulfation, glycosaminoglycan modification, or acylation of the presenilins was not observed, but both proteins are posttranslationally phosphorylated on serine residues. The mutations Ala-246 → Glu or Cys-410 → Tyr that cause Alzheimer's disease do not interfere with the biosynthesis or phosphorylation of presenilin 1. Finally, using low concentrations of digitonin to selectively permeabilize the cell membrane but not the endoplasmic reticulum membrane, it is demonstrated that the two major hydrophilic domains of presenilin 1 are oriented to the cytoplasm. The current investigation documents the posttranslational modifications and subcellular localization of the presenilins and indicates that postulated interactions with amyloid precursor protein metabolism should occur in the early compartments of the biosynthetic pathway. Presenilins 1 and 2 are unglycosylated proteins with apparent molecular mass of 45 and 50 kDa, respectively, in transfected COS-1 and Chinese hamster ovary cells. They colocalize with proteins from the endoplasmic reticulum and the Golgi apparatus in transfected and untransfected cells. In COS-1 cells low amounts of intact endogeneous presenilin 1 migrating at 45 kDa are detected together with relative larger amounts of presenilin 1 fragments migrating between 18 and 30 kDa. The presenilins have a strong tendency to form aggregates (mass of 100-250 kDa) in SDS-polyacrylamide gel electrophoresis, which can be partially resolved when denatured by SDS at 37°C instead of 95°C. Sulfation, glycosaminoglycan modification, or acylation of the presenilins was not observed, but both proteins are posttranslationally phosphorylated on serine residues. The mutations Ala-246 → Glu or Cys-410 → Tyr that cause Alzheimer's disease do not interfere with the biosynthesis or phosphorylation of presenilin 1. Finally, using low concentrations of digitonin to selectively permeabilize the cell membrane but not the endoplasmic reticulum membrane, it is demonstrated that the two major hydrophilic domains of presenilin 1 are oriented to the cytoplasm. The current investigation documents the posttranslational modifications and subcellular localization of the presenilins and indicates that postulated interactions with amyloid precursor protein metabolism should occur in the early compartments of the biosynthetic pathway. INTRODUCTIONAlzheimer's disease is a major health problem. Patients suffer from a progressive dementia caused by massive neuronal loss in cortical and hippocampal areas of the brain (1Haass C. Selkoe D.J. Cell. 1993; 75: 1039-1042Abstract Full Text PDF PubMed Scopus (736) Google Scholar, 2Selkoe D.J. Annu. Rev. Cell Biol. 1994; 10: 373-403Crossref PubMed Scopus (736) Google Scholar, 3Checler F. J. Neurochem. 1995; 65: 1431-1444Crossref PubMed Scopus (420) Google Scholar, 4Kosik K.S. J. Cell Biol. 1994; 127: 1501-1504Crossref PubMed Scopus (31) Google Scholar, 5Haass C. Curr. Opin. Neurol. 1996; 9: 254-259Crossref PubMed Scopus (50) Google Scholar, 6Strittmatter W.J. Roses A.D. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4725-4727Crossref PubMed Scopus (440) Google Scholar). Neuropathological signs of the disease are tangles and amyloid deposits in the brain parenchyma, and amyloid deposits in the brain vasculature. The cause of the sporadic form of the disease is still unknown, although an increased risk is associated with the presence of apolipoprotein allele E4 (6Strittmatter W.J. Roses A.D. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4725-4727Crossref PubMed Scopus (440) Google Scholar, 7Rebeck G.W. Reiter J.S. Strickland D.K. Hyman B.T. Neuron. 1993; 11: 575-580Abstract Full Text PDF PubMed Scopus (966) Google Scholar). On the other hand, familial early onset Alzheimer's disease is caused by point mutations in the amyloid precursor protein gene on chromosome 21 (8Goate A. Chartier-Harlin M.C. Mullan M. Brown J. Crawford F. Fidani L. Giuffra L. Haynes A. Irving N. James L. Mant R. Newton P. Rooke K. Roques P. Talbot C. Pericak-Vance M. Roses A. Williamson Rossor M. Owen M. Hardy J. Nature. 1991; 349: 704-706Crossref PubMed Scopus (3719) Google Scholar), in the presenilin 2 (PS2) 1The abbreviations used are: PS2presenilin 2PS1presenilin 1APPamyloid precursor proteinmAbmonoclonal antibodyPBSphosphate-buffered salineTBSTris-buffered salineFITCfluorescein isothiocyanateTRITCtetramethylrhodamine isothiocyanatePAGEpolyacrylamide gel electrophoresisPipes1,4-piperazinediethanesulfonic acidNSPneuroendocrine-specific protein. gene on chromosome 1 (9Rogaev E.I. Sherrington R. Rogaeva E.A. Levesque G. Ikeda M. Liang Y. Chi H. Lin C. Holamn K. Tsuda T. Mar L. Sorbi S. Nacmias B. Piacenti S. Amaducci L. Chumakov I. Cohen D. Lannfelt L. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 376: 775-778Crossref PubMed Scopus (1773) Google Scholar, 10Levy-Lahad E. Wasco W. Poorkaj P. Romano D.M. Osima J. Pettingell H. Yu C. Jondro P.D. Schmidt S.D. Wang K. Crowley A.C. Fu Y.H. Guenette S.Y. Galas D. Nemens E. Wijsman E.M. Bird T.D. Schellenberg G.D. Tanzi R.E. Science. 1995; 269: 973-977Crossref PubMed Scopus (2213) Google Scholar, 11Li J. Ma J. Potter H. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 12180-12184Crossref PubMed Scopus (50) Google Scholar), or, most frequently, in the presenilin 1 (PS1) gene on chromosome 14 (12Sherrington R. Rogaev E.I. Liang Y. Rogaeva E.A. Levesque G. Ikeda M. Chi H. Lin C. Li G. Holman K. Tsuda T. Mar L. Foncin J.F. Bruni A.C. Montesi M.P. Sorbi S. Rainero I. Pinessi L. Nee L. Chumakov I. Pollen D. Brookes A. Sanseau P. Polnsky R.J. Wasco W. da Silva H.A.R. Haines J.L. Pericak-Vance M.A. Tanzi R.E. Roses A.D. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 375: 754-760Crossref PubMed Scopus (3555) Google Scholar, 13Alzheimer's Disease Collaborative Group, (1995) Nat. Genet., 11, 219–222.Google Scholar, 14Wasco W. Pettingell W.P. Jondro P.D. Schmidt S.D. Gurubhagavatula S. Rodes L. DiBlasi T. Romano T.M. Guenette S.Y. Kovacs D.M. Growdon J.H. Tanzi R.E. Nat. Med. 1995; 1: 848Crossref PubMed Scopus (108) Google Scholar, 15Van Broeckhoven C. Nat. Genet. 1995; 11: 230-232Crossref PubMed Scopus (206) Google Scholar). Amyloid precursor protein (APP) is a type I integral membrane protein and is the precursor of the amyloid peptide, the main component of the senile plaques (1Haass C. Selkoe D.J. Cell. 1993; 75: 1039-1042Abstract Full Text PDF PubMed Scopus (736) Google Scholar, 2Selkoe D.J. Annu. Rev. Cell Biol. 1994; 10: 373-403Crossref PubMed Scopus (736) Google Scholar, 3Checler F. J. Neurochem. 1995; 65: 1431-1444Crossref PubMed Scopus (420) Google Scholar). Point mutations in exons 16 and 17 of the APP gene cause alterations in the metabolism of APP. This results in an increased production of intracellular βA4 amyloid peptide containing carboxyl-terminal APP fragments and in an increased secretion of the potentially neurotoxic βA4 peptide (1Haass C. Selkoe D.J. Cell. 1993; 75: 1039-1042Abstract Full Text PDF PubMed Scopus (736) Google Scholar, 2Selkoe D.J. Annu. Rev. Cell Biol. 1994; 10: 373-403Crossref PubMed Scopus (736) Google Scholar, 3Checler F. J. Neurochem. 1995; 65: 1431-1444Crossref PubMed Scopus (420) Google Scholar, 16De Strooper B. Simons M. Multhaup G. Van Leuven F. Beyreuther K. Dotti C.G. EMBO J. 1995; 14: 4932-4938Crossref PubMed Scopus (161) Google Scholar). 63% of the amino acid residues in the sequences of the two presenilins are conserved, which strongly suggests that both proteins are involved in similar functions and have a similar in Alzheimer's on membrane domains have (9Rogaev E.I. Sherrington R. Rogaeva E.A. Levesque G. Ikeda M. Liang Y. Chi H. Lin C. Holamn K. Tsuda T. Mar L. Sorbi S. Nacmias B. Piacenti S. Amaducci L. Chumakov I. Cohen D. Lannfelt L. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 376: 775-778Crossref PubMed Scopus (1773) Google Scholar, 10Levy-Lahad E. Wasco W. Poorkaj P. Romano D.M. Osima J. Pettingell H. Yu C. Jondro P.D. Schmidt S.D. Wang K. Crowley A.C. Fu Y.H. Guenette S.Y. Galas D. Nemens E. Wijsman E.M. Bird T.D. Schellenberg G.D. Tanzi R.E. Science. 1995; 269: 973-977Crossref PubMed Scopus (2213) Google Scholar, 11Li J. Ma J. Potter H. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 12180-12184Crossref PubMed Scopus (50) Google Scholar, R. Rogaev E.I. Liang Y. Rogaeva E.A. Levesque G. Ikeda M. Chi H. Lin C. Li G. Holman K. Tsuda T. Mar L. Foncin J.F. Bruni A.C. Montesi M.P. Sorbi S. Rainero I. Pinessi L. Nee L. Chumakov I. Pollen D. Brookes A. Sanseau P. Polnsky R.J. Wasco W. da Silva H.A.R. Haines J.L. Pericak-Vance M.A. Tanzi R.E. Roses A.D. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 375: 754-760Crossref PubMed Scopus (3555) Google Scholar, 13Alzheimer's Disease Collaborative Group, (1995) Nat. Genet., 11, 219–222.Google Scholar, 14Wasco W. Pettingell W.P. Jondro P.D. Schmidt S.D. Gurubhagavatula S. Rodes L. DiBlasi T. Romano T.M. Guenette S.Y. Kovacs D.M. Growdon J.H. Tanzi R.E. Nat. Med. 1995; 1: 848Crossref PubMed Scopus (108) Google Scholar, 15Van Broeckhoven C. Nat. Genet. 1995; 11: 230-232Crossref PubMed Scopus (206) Google Scholar), although the of domains be at G. J. 1995; Scholar). The and the between domains and are hydrophilic and can be (9Rogaev E.I. Sherrington R. Rogaeva E.A. Levesque G. Ikeda M. Liang Y. Chi H. Lin C. Holamn K. Tsuda T. Mar L. Sorbi S. Nacmias B. Piacenti S. Amaducci L. Chumakov I. Cohen D. Lannfelt L. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 376: 775-778Crossref PubMed Scopus (1773) Google Scholar, 13Alzheimer's Disease Collaborative Group, (1995) Nat. Genet., 11, 219–222.Google Scholar). The mutations that cause familial Alzheimer's disease are the but the hydrophilic a with mutations to C. Curr. Opin. Neurol. 1996; 9: 254-259Crossref PubMed Scopus (50) Google Scholar, 15Van Broeckhoven C. Nat. Genet. 1995; 11: 230-232Crossref PubMed Scopus (206) Google Scholar). The of the presenilins unknown, the carboxyl-terminal amino acid residues of can in a E. L. Science. 1996; PubMed Scopus Google Scholar). on the with in intracellular protein have J. Cell Biol. PubMed Scopus Google Scholar, D. I. Nature. 1995; PubMed Scopus Google in the of the and sporadic of Alzheimer's disease on the of the amyloid the tangles and the in The is mutations in the presenilin can cause an increased production of peptide in from with presenilin mutations the amyloid that βA4 amyloid peptide production and the in the of the disease D.J. Annu. Rev. Cell Biol. 1994; 10: 373-403Crossref PubMed Scopus (736) Google Scholar, D. C. M. M. N. Bird T.D. Hardy J. M. W. E. E. M. E. Poorkaj P. Schellenberg G. Tanzi R. Wasco W. Lannfelt L. Selkoe D. S. Nat. Med. 1996; PubMed Scopus Google Scholar). the in peptide production and the between presenilin mutations and APP metabolism should be by the of presenilin mutations on APP in transfected cells or in of other of APP metabolism the production of carboxyl-terminal APP fragments Strooper B. Simons M. Multhaup G. Van Leuven F. Beyreuther K. Dotti C.G. EMBO J. 1995; 14: 4932-4938Crossref PubMed Scopus (161) Google should be in The that presenilins with the or should not be at E. L. Science. 1996; PubMed Scopus Google Scholar). In to is on the subcellular the posttranslational and the membrane of the used COS-1 cells and cells to and and mutations that cause familial Alzheimer's The biosynthesis of transfected and untransfected presenilins was using or and that transfected presenilins are phosphorylated on serine residues. the of presenilin 1 with the early compartments of the biosynthetic and the of the two major hydrophilic current investigation a of the biosynthesis of presenilins in COS-1 cells and cells. The results that the proteins are unglycosylated with apparent molecular of 45 and 50 kDa in They have a strong tendency to form with apparent molecular between and kDa. that is in the endoplasmic reticulum and the Golgi apparatus and that and the hydrophilic are oriented to the localization of transfected in the endoplasmic reticulum of COS-1 cells or cells is not a of of the protein or on the biosynthetic in cells. endogeneous presenilins are in the endoplasmic reticulum of untransfected cells demonstrated in using using APP and to in the Golgi demonstrated G. C. Tanzi R.E. J. Biol. 1994; 269: Full Text PDF PubMed Google Scholar, Strooper B. K. Van Leuven F. Van H. J. Biol. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). the and the of APP Strooper and K. in cells was not by of on protein and On the other hand, the of endogeneous presenilin in COS-1 cells are the of to from of by using to endogeneous migrating at the molecular transfected The of is that the from the interfere with the of in the This a of the metabolism of the presenilins using and On the other hand, it to the presence or of on the of hydrophilic in the in the of relative amounts fragments of in the The of fragments was or increased in COS-1 cells that which not detected in the The involved is or by G. L. G. T. F. C. M. Hardy J. Neuron. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, M. H. T. K. M. Y. K. K. A. 1996; PubMed Scopus Google Scholar). do not to on the or the of can that of the type used are not to of presenilin On the other hand, it is that untransfected cells and brain in M. H. T. K. M. Y. K. K. A. 1996; PubMed Scopus Google Scholar, N. J. J. C. Li J.M. S. J. 1996; PubMed Scopus Google amounts of intact the transfected the that transfected are not to glycosaminoglycan modification, or the endogeneous protein. posttranslational modifications are to the of the molecular aggregates kDa) in aggregates to a in and by using other cell or brain M. H. T. K. M. Y. K. K. A. 1996; PubMed Scopus Google Scholar, D.M. H. R. Hyman B.T. Tanzi R.E. Wasco W. Nat. Med. 1996; Scopus Google Scholar, S. C. L. B. M. A. F. 1996; PubMed Scopus Google Scholar). the detected with and by a using a the aggregates presenilin or associated with of at 37°C instead of in aggregates and increased amounts of the The aggregates of of is to form aggregates in in but that of presenilins in the endoplasmic reticulum of untransfected should be that in of presenilins a problem. In it should be that amyloid plaques in the of Alzheimer's disease T. J. B. 1995; PubMed Google the two point mutations Alzheimer's disease that Ala-246 → Glu and Cys-410 → Tyr not the biosynthesis or of of the protein in COS-1 cells and cells. mutations cause The that interfere with the of was two other mutations G. L. G. T. F. C. M. Hardy J. Neuron. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, M. H. T. K. M. Y. K. K. A. 1996; PubMed Scopus Google Scholar), be from the current of of the Ala-246 → Glu that at not interfere with the of B. and F. Van mutations to in a in the of Alzheimer's a of is most that from with presenilin mutations and of the βA4 amyloid peptide suggests that the mutations on metabolism or of amyloid precursor protein D. C. M. M. N. Bird T.D. Hardy J. M. W. E. E. M. E. Poorkaj P. Schellenberg G. Tanzi R. Wasco W. Lannfelt L. Selkoe D. S. Nat. Med. 1996; PubMed Scopus Google Scholar). The localization of in the early compartments of the biosynthetic it that the presenilin mutations in the and at the cell and in Strooper B. L. Van Leuven F. Van H. J. Cell Biol. 1993; PubMed Scopus Google Scholar, J. Biol. 1994; 269: Full Text PDF PubMed Google Scholar, G. R. B. J. Biol. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, C. A. M. P. D. Lannfelt L. Selkoe D. Nat. Med. 1995; 1: PubMed Scopus Google Scholar). The that the between and of APP in an by intracellular should be in cells and Strooper B. Simons M. Multhaup G. Van Leuven F. Beyreuther K. Dotti C.G. EMBO J. 1995; 14: 4932-4938Crossref PubMed Scopus (161) Google Scholar, C. A. Selkoe D.J. J. Cell Biol. 1995; PubMed Scopus Google Scholar, Strooper B. K. I. D. B. Van Leuven F. Van H. J. Biol. 1995; Full Text Full Text PDF PubMed Scopus Google that the presenilins are phosphorylated on serine residues. of and was both in COS-1 cells and but the phosphorylation of was and of The that acid the phosphorylation suggests that is to is not of cells by to or in increased is that the presenilins are involved in the of APP secretion by protein P. P. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, PubMed Scopus Google that the hydrophilic and the major of are to the of the endoplasmic reticulum at low concentrations selectively the cell membrane, but not the endoplasmic reticulum membrane J. Biol. 1994; 269: Full Text PDF PubMed Google Scholar). the of similar in digitonin and cells. with a the endoplasmic reticulum M.A. M.A. G.W. PubMed Scopus Google Scholar, S. Cell. Full Text PDF PubMed Scopus Google Scholar), that digitonin not permeabilize the endoplasmic reticulum the major hydrophilic results The is that the two major hydrophilic domains in are oriented to the of the endoplasmic which the proteins with domains the cytoplasm. with the with but not digitonin This not the localization of the but the it was and are to the of the presenilins in the endoplasmic reticulum membrane, results two The is the of the in which in the of the domains P. P. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). The between the carboxyl-terminal and the residues the membrane suggests a of amino E. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). to are of proteins of which the 17 amino acid residues E. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). In which The which by (9Rogaev E.I. Sherrington R. Rogaeva E.A. Levesque G. Ikeda M. Liang Y. Chi H. Lin C. Holamn K. Tsuda T. Mar L. Sorbi S. Nacmias B. Piacenti S. Amaducci L. Chumakov I. Cohen D. Lannfelt L. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 376: 775-778Crossref PubMed Scopus (1773) Google Scholar, 13Alzheimer's Disease Collaborative Group, (1995) Nat. Genet., 11, 219–222.Google Scholar, G. J. 1995; Scholar), is two in the amino acid the hydrophilic can the membrane, which the presenilins are with a with the and the hydrophilic in the in In the current the biosynthesis and the subcellular localization of the presenilins and a the of cell and interactions with integral membrane and proteins APP or both in the of Alzheimer's disease K.S. J. Cell Biol. 1994; 127: 1501-1504Crossref PubMed Scopus (31) Google in with in the the endoplasmic reticulum membrane, is with This in a of the carboxyl-terminal of INTRODUCTIONAlzheimer's disease is a major health problem. Patients suffer from a progressive dementia caused by massive neuronal loss in cortical and hippocampal areas of the brain (1Haass C. Selkoe D.J. Cell. 1993; 75: 1039-1042Abstract Full Text PDF PubMed Scopus (736) Google Scholar, 2Selkoe D.J. Annu. Rev. Cell Biol. 1994; 10: 373-403Crossref PubMed Scopus (736) Google Scholar, 3Checler F. J. Neurochem. 1995; 65: 1431-1444Crossref PubMed Scopus (420) Google Scholar, 4Kosik K.S. J. Cell Biol. 1994; 127: 1501-1504Crossref PubMed Scopus (31) Google Scholar, 5Haass C. Curr. Opin. Neurol. 1996; 9: 254-259Crossref PubMed Scopus (50) Google Scholar, 6Strittmatter W.J. Roses A.D. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4725-4727Crossref PubMed Scopus (440) Google Scholar). Neuropathological signs of the disease are tangles and amyloid deposits in the brain parenchyma, and amyloid deposits in the brain vasculature. The cause of the sporadic form of the disease is still unknown, although an increased risk is associated with the presence of apolipoprotein allele E4 (6Strittmatter W.J. Roses A.D. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 4725-4727Crossref PubMed Scopus (440) Google Scholar, 7Rebeck G.W. Reiter J.S. Strickland D.K. Hyman B.T. Neuron. 1993; 11: 575-580Abstract Full Text PDF PubMed Scopus (966) Google Scholar). On the other hand, familial early onset Alzheimer's disease is caused by point mutations in the amyloid precursor protein gene on chromosome 21 (8Goate A. Chartier-Harlin M.C. Mullan M. Brown J. Crawford F. Fidani L. Giuffra L. Haynes A. Irving N. James L. Mant R. Newton P. Rooke K. Roques P. Talbot C. Pericak-Vance M. Roses A. Williamson Rossor M. Owen M. Hardy J. Nature. 1991; 349: 704-706Crossref PubMed Scopus (3719) Google Scholar), in the presenilin 2 (PS2) 1The abbreviations used are: PS2presenilin 2PS1presenilin 1APPamyloid precursor proteinmAbmonoclonal antibodyPBSphosphate-buffered salineTBSTris-buffered salineFITCfluorescein isothiocyanateTRITCtetramethylrhodamine isothiocyanatePAGEpolyacrylamide gel electrophoresisPipes1,4-piperazinediethanesulfonic acidNSPneuroendocrine-specific protein. gene on chromosome 1 (9Rogaev E.I. Sherrington R. Rogaeva E.A. Levesque G. Ikeda M. Liang Y. Chi H. Lin C. Holamn K. Tsuda T. Mar L. Sorbi S. Nacmias B. Piacenti S. Amaducci L. Chumakov I. Cohen D. Lannfelt L. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 376: 775-778Crossref PubMed Scopus (1773) Google Scholar, 10Levy-Lahad E. Wasco W. Poorkaj P. Romano D.M. Osima J. Pettingell H. Yu C. Jondro P.D. Schmidt S.D. Wang K. Crowley A.C. Fu Y.H. Guenette S.Y. Galas D. Nemens E. Wijsman E.M. Bird T.D. Schellenberg G.D. Tanzi R.E. Science. 1995; 269: 973-977Crossref PubMed Scopus (2213) Google Scholar, 11Li J. Ma J. Potter H. Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 12180-12184Crossref PubMed Scopus (50) Google Scholar), or, most frequently, in the presenilin 1 (PS1) gene on chromosome 14 (12Sherrington R. Rogaev E.I. Liang Y. Rogaeva E.A. Levesque G. Ikeda M. Chi H. Lin C. Li G. Holman K. Tsuda T. Mar L. Foncin J.F. Bruni A.C. Montesi M.P. Sorbi S. Rainero I. Pinessi L. Nee L. Chumakov I. Pollen D. Brookes A. Sanseau P. Polnsky R.J. Wasco W. da Silva H.A.R. Haines J.L. Pericak-Vance M.A. Tanzi R.E. Roses A.D. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 375: 754-760Crossref PubMed Scopus (3555) Google Scholar, 13Alzheimer's Disease Collaborative Group, (1995) Nat. Genet., 11, 219–222.Google Scholar, 14Wasco W. Pettingell W.P. Jondro P.D. Schmidt S.D. Gurubhagavatula S. Rodes L. DiBlasi T. Romano T.M. Guenette S.Y. Kovacs D.M. Growdon J.H. Tanzi R.E. Nat. Med. 1995; 1: 848Crossref PubMed Scopus (108) Google Scholar, 15Van Broeckhoven C. Nat. Genet. 1995; 11: 230-232Crossref PubMed Scopus (206) Google Scholar). Amyloid precursor protein (APP) is a type I integral membrane protein and is the precursor of the amyloid peptide, the main component of the senile plaques (1Haass C. Selkoe D.J. Cell. 1993; 75: 1039-1042Abstract Full Text PDF PubMed Scopus (736) Google Scholar, 2Selkoe D.J. Annu. Rev. Cell Biol. 1994; 10: 373-403Crossref PubMed Scopus (736) Google Scholar, 3Checler F. J. Neurochem. 1995; 65: 1431-1444Crossref PubMed Scopus (420) Google Scholar). Point mutations in exons 16 and 17 of the APP gene cause alterations in the metabolism of APP. This results in an increased production of intracellular βA4 amyloid peptide containing carboxyl-terminal APP fragments and in an increased secretion of the potentially neurotoxic βA4 peptide (1Haass C. Selkoe D.J. Cell. 1993; 75: 1039-1042Abstract Full Text PDF PubMed Scopus (736) Google Scholar, 2Selkoe D.J. Annu. Rev. Cell Biol. 1994; 10: 373-403Crossref PubMed Scopus (736) Google Scholar, 3Checler F. J. Neurochem. 1995; 65: 1431-1444Crossref PubMed Scopus (420) Google Scholar, 16De Strooper B. Simons M. Multhaup G. Van Leuven F. Beyreuther K. Dotti C.G. EMBO J. 1995; 14: 4932-4938Crossref PubMed Scopus (161) Google Scholar). 63% of the amino acid residues in the sequences of the two presenilins are conserved, which strongly suggests that both proteins are involved in similar functions and have a similar in Alzheimer's on membrane domains have (9Rogaev E.I. Sherrington R. Rogaeva E.A. Levesque G. Ikeda M. Liang Y. Chi H. Lin C. Holamn K. Tsuda T. Mar L. Sorbi S. Nacmias B. Piacenti S. Amaducci L. Chumakov I. Cohen D. Lannfelt L. Fraser P.E. Rommens J.M. St. George-Hyslop P.H. Nature. 1995; 376: 775-778Crossref PubMed Scopus (1773) Google Scholar, 10Levy-Lahad E. Wasco W. Poorkaj P. 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