SREBP cleavage-activating protein (SCAP) stimulates the proteolytic cleavage of membrane-bound SREBPs, thereby initiating the release of NH2-terminal fragments from cell membranes. The liberated fragments enter the nucleus and stimulate transcription of genes involved in synthesis and uptake of cholesterol and fatty acids. Sterols repress cleavage of SREBPs, apparently by interacting with the membrane attachment domain of SCAP. In the present studies we show that SCAP, like the SREBPs, is located in membranes of the endoplasmic reticulum and nuclear envelope. The COOH-terminal domain of SCAP, like that of the SREBPs, is located on the cytosolic face of the membranes. Co-immunoprecipitation experiments show that SCAP and SREBP-2 form a complex that can be precipitated with antibodies to either component. Complex formation occurs when cells express only the COOH-terminal domain of either SREBP-2 or SCAP, indicating that the complex forms between the two COOH-terminal domains. Truncation of SREBP-2 at its COOH terminus prevents the formation of complexes with SCAP and simultaneously reduces proteolytic cleavage. We conclude that proteolytic cleavage of SREBPs requires the formation of a complex with the COOH-terminal domain of SCAP and that SCAP is therefore a required element in the regulation of sterol and fatty acid metabolism in animal cells. SREBP cleavage-activating protein (SCAP) stimulates the proteolytic cleavage of membrane-bound SREBPs, thereby initiating the release of NH2-terminal fragments from cell membranes. The liberated fragments enter the nucleus and stimulate transcription of genes involved in synthesis and uptake of cholesterol and fatty acids. Sterols repress cleavage of SREBPs, apparently by interacting with the membrane attachment domain of SCAP. In the present studies we show that SCAP, like the SREBPs, is located in membranes of the endoplasmic reticulum and nuclear envelope. The COOH-terminal domain of SCAP, like that of the SREBPs, is located on the cytosolic face of the membranes. Co-immunoprecipitation experiments show that SCAP and SREBP-2 form a complex that can be precipitated with antibodies to either component. Complex formation occurs when cells express only the COOH-terminal domain of either SREBP-2 or SCAP, indicating that the complex forms between the two COOH-terminal domains. Truncation of SREBP-2 at its COOH terminus prevents the formation of complexes with SCAP and simultaneously reduces proteolytic cleavage. We conclude that proteolytic cleavage of SREBPs requires the formation of a complex with the COOH-terminal domain of SCAP and that SCAP is therefore a required element in the regulation of sterol and fatty acid metabolism in animal cells. Sterol regulatory element-binding proteins (SREBPs) 1The abbreviations used are: SREBP, sterol regulatory element-binding protein; ER, endoplasmic reticulum, HMG, 3-hydroxy-3-methylglutaryl; CoA, coenzyme A; HSV, herpes simplex virus; PBS, phosphate-buffered saline; PCR, polymerase chain reaction; SCAP, SREBP cleavage-activating protein; kb, kilobase(s). are membrane-bound transcription factors that regulate the synthesis and uptake of cholesterol and fatty acids in animal cells (reviewed in Ref. 1Brown M.S. Goldstein J.L. Cell. 1997; 89: 331-340Abstract Full Text Full Text PDF PubMed Scopus (3002) Google Scholar). Two SREBPs, designated SREBP-1a and SREBP-2, predominate in cultured cells. The activities of both SREBPs are regulated by the sterol content of the cells. When cells are replete with sterols, the SREBPs remain bound to membranes of the endoplasmic reticulum (ER) and nuclear envelope and are therefore inactive. When cells are depleted of sterols, a proteolytic process releases the active portions of the SREBPs, which enter the nucleus and stimulate transcription of genes in three pathways of lipid metabolism: 1) cholesterol biosynthesis (HMG-CoA synthase, HMG-CoA reductase, farnesyl diphosphate synthase, and squalene synthase) (1Brown M.S. Goldstein J.L. Cell. 1997; 89: 331-340Abstract Full Text Full Text PDF PubMed Scopus (3002) Google Scholar, 2Ericsson J. Jackson S.M. Lee B.C. Edwards P.A. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 945-950Crossref PubMed Scopus (156) Google Scholar, 3Guan G. Jiang G. Koch R.L. Shechter I. J. Biol. Chem. 1995; 270: 21958-21965Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar, 4Vallett S.M. Sanchez H.B. Rosenfeld J.M. Osborne T.F. J. Biol. Chem. 1996; 271: 12247-12253Abstract Full Text Full Text PDF PubMed Scopus (205) Google Scholar); 2) uptake of cholesterol and fatty acids from plasma (low density lipoprotein receptor and lipoprotein lipase) (1Brown M.S. Goldstein J.L. Cell. 1997; 89: 331-340Abstract Full Text Full Text PDF PubMed Scopus (3002) Google Scholar, 5Kim J.B. Spiegelman B.M. Genes Dev. 1996; 10: 1096-1107Crossref PubMed Scopus (846) Google Scholar); and 3) fatty acid biosynthesis (acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase-1) (1Brown M.S. Goldstein J.L. Cell. 1997; 89: 331-340Abstract Full Text Full Text PDF PubMed Scopus (3002) Google Scholar, 5Kim J.B. Spiegelman B.M. Genes Dev. 1996; 10: 1096-1107Crossref PubMed Scopus (846) Google Scholar, 6Bennett M.K. Lopez J.M. Sanchez H.B. Osborne T.F. J. Biol. Chem. 1995; 270: 25578-25583Abstract Full Text Full Text PDF PubMed Scopus (333) Google Scholar, 7Shimano H. Horton J.D. Hammer R.E. Shimomura I. Brown M.S. Goldstein J.L. J. Clin. Invest. 1996; 98: 1575-1584Crossref PubMed Scopus (698) Google Scholar). The mechanism by which sterols control the proteolytic release of SREBPs from cell membranes is beginning to be elucidated through studies of cultured animal cells (1Brown M.S. Goldstein J.L. Cell. 1997; 89: 331-340Abstract Full Text Full Text PDF PubMed Scopus (3002) Google Scholar). These studies revealed that the SREBPs are tripartite proteins of ∼1150 amino acids that are attached to membranes in a hairpin fashion (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google Scholar, 9Duncan E.A. Brown M.S. Goldstein J.L. Sakai J. J. Biol. Chem. 1997; 272: 12778-12785Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar). The NH2-terminal segment of ∼480 amino acids, which faces the cytoplasm, is a classic transcription factor of the basic-helix-loop-helix-leucine zipper family. This segment is followed by a hairpin-like membrane attachment domain that consists of two membrane-spanning sequences separated by a hydrophilic loop of ∼30 amino acids that projects into the lumen of the ER or nuclear envelope. This is followed by a COOH-terminal segment of ∼590 amino acids that projects into the cytoplasm. In sterol-depleted cells, a protease clips each SREBP at Site-1, which is a Leu-Ser bond in the middle of the lumenal loop (9Duncan E.A. Brown M.S. Goldstein J.L. Sakai J. J. Biol. Chem. 1997; 272: 12778-12785Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar, 10Sakai J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). This the bond between the two membrane-spanning and a protease to at which to be in the middle of the segment J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). at releases the NH2-terminal which the apparently with a of the membrane-spanning The NH2-terminal segment the to sterol regulatory in the of the genes thereby transcription (1Brown M.S. Goldstein J.L. Cell. 1997; 89: 331-340Abstract Full Text Full Text PDF PubMed Scopus (3002) Google Scholar). When cells are with sterols, at is at cleavage requires at (9Duncan E.A. Brown M.S. Goldstein J.L. Sakai J. J. Biol. Chem. 1997; 272: 12778-12785Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar, 10Sakai J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). a the NH2-terminal remain bound to and transcription of the genes is The of the that at and are The requires that is three to the NH2-terminal of the Leu-Ser bond (9Duncan E.A. Brown M.S. Goldstein J.L. Sakai J. J. Biol. Chem. 1997; 272: 12778-12785Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar, 10Sakai J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). and SREBP-2, J. Goldstein J.L. Brown M.S. Genes Dev. PubMed Scopus Google Scholar, X. J. Brown M.S. Goldstein J.L. X. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). on the lumenal of the the requires the COOH-terminal domain of the When domain in SREBP-2 is through cleavage by the protease is S. and J. The requires the which is to the domain J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). a protein designated SREBP cleavage-activating protein (SCAP) that to sterol regulation of cleavage at X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). a form of SCAP by from a of cells with a in sterol In cells sterols cleavage of SREBPs at Site-1, and the cells to a of acid at of SCAP. When a the of SCAP is into cells, the cells show cleavage of SREBPs at Site-1, and sterols cleavage. of a SCAP can a the is at X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). We from that SCAP stimulates cleavage at and that its is by The SCAP is both and to by The the of SCAP is by of the of the acid which that SCAP is into two domains. The NH2-terminal domain of amino acids consists of and hydrophilic that are with membrane-spanning X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). This is followed by a COOH-terminal domain of amino acids that is hydrophilic and or of amino acids are in proteins of the of proteins T.F. PubMed Scopus Google Scholar). The proteins that are to form a the of which between the and the and of the Lee Cell. 1995; Full Text PDF PubMed Scopus Google Scholar, J. A. 1996; PubMed Scopus Google Scholar). are in to The of SCAP is the of its membrane domain to the membrane domain of HMG-CoA reductase, ER involved in cholesterol synthesis X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). SCAP, HMG-CoA is into two portions J. Brown M.S. Goldstein J.L. J. Biol. Chem. Full Text PDF PubMed Google Scholar). The NH2-terminal of the protein membrane-spanning J. Biol. Chem. Full Text PDF PubMed Google Scholar). The COOH-terminal of the which projects into the cytoplasm, the domain of the J. Brown M.S. Goldstein J.L. J. Biol. Chem. Full Text PDF PubMed Google Scholar). The membrane domain is of the G. Goldstein J.L. Brown M.S. Cell. Full Text PDF PubMed Scopus Google Scholar, H. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). 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In the studies we to the mechanism by which SCAP regulate the cleavage of of a we show that the COOH-terminal domain of SREBP-2 forms a complex with the COOH-terminal domain of SCAP. We that SCAP to a protease that SREBPs at This the that cleavage at requires the COOH-terminal domain of We antibodies and from from and from Jackson and from from (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google X. Sakai J. Brown M.S. Goldstein J.L. J. Biol. Chem. 1996; 271: Full Text Full Text PDF PubMed Scopus Google Scholar). is protein with two NH2-terminal control of the J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). is protein at the by two and at the COOH terminus by three of from the protein (9Duncan E.A. Brown M.S. Goldstein J.L. Sakai J. J. Biol. Chem. 1997; 272: 12778-12785Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar). is a SCAP that is to X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google that the from to The amino acids of SREBP-2 by two of the and two amino acids by a the Ref. X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google with and the the and amino acids of SREBP-2 the to amino acids of SREBP-2 by (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google of Ref. X. Sakai J. Brown M.S. Goldstein J.L. J. Biol. Chem. 1996; 271: Full Text Full Text PDF PubMed Scopus Google with NH2-terminal by and a COOH-terminal by The to the to The a protein of two of the two amino acids by the amino acids of SREBP-2, two amino acids by the amino acids of and three of the (9Duncan E.A. Brown M.S. Goldstein J.L. Sakai J. J. Biol. Chem. 1997; 272: 12778-12785Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar). Ref. X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google with to a the followed by SREBP-2 acids Ref. 9Duncan E.A. Brown M.S. Goldstein J.L. Sakai J. J. Biol. Chem. 1997; 272: 12778-12785Abstract Full Text Full Text PDF PubMed Scopus (154) Google with to a a protein of SREBP-2 acids acids and three of the The fragments to and and the with the to The a protein of amino acids of SCAP, and three of the the to amino acids of SCAP by of X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google with a of amino acids of SCAP by and and amino acids of The into the and with which in the of the and to a amino acids of SCAP. by of with and and the amino acids of SCAP with the amino acids to the Ref. X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google with and the amino acids of SCAP and three of the used to amino acids of SCAP in The of the by fragments and with J.D. PubMed Scopus Google the (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google Scholar). to the and at two of each into cells to the SCAP by with a of two followed by amino acids of SCAP and the followed by amino acids of SCAP X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). SCAP by a J. Ho Y.K. Brown M.S. Goldstein J.L. J. Biol. Chem. Full Text PDF PubMed Google with a protein followed by amino acids of SCAP X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). The the proteins into and in and the proteins by X. A. J. X. Goldstein J.L. Brown M.S. Cell. Full Text PDF PubMed Scopus Google Scholar). antibodies the domain of J. X. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. Full Text PDF PubMed Google SREBP-2 acids J. Goldstein J.L. Brown M.S. Genes Dev. PubMed Scopus Google and the COOH terminus of SREBP-2 acids (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google in the antibodies of cells on and cultured in at in and with the cells with the (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google Scholar). the cells to and in the or of sterols cholesterol in a of in the cells from two used either and membrane J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google or the cells Goldstein J.L. Brown M.S. J. Biol. Chem. Full Text PDF PubMed Google on at a density of in of and and with J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). cells with of is the to The on with in the of The cell by with and the from of cells and the cell with of at and through a and by at at The cell by at in a of the of protein in to a of with and by with either of Ref. H. Goldstein J.L. Brown M.S. Cell. Full Text PDF PubMed Scopus (148) Google with or of of with a and of with a at in a at the to a and or antibodies of followed by and at The to a and precipitated with of at followed by at The in of at and and designated the of the The the on the with of followed by in The in of at and and at at the to a and designated the of the to the and each of and to and The proteins to which with of the antibodies antibodies with or the to the with to at the studies that the forms of the SREBPs are bound to membranes of the ER and nuclear by of cells J. X. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. Full Text PDF PubMed Google Scholar, X. Brown M.S. X. Goldstein J.L. Cell. Full Text PDF PubMed Scopus Google Scholar). SCAP is we a of cells that of SCAP a of with of cells with a SCAP revealed that the protein is located in membranes of the ER and nuclear envelope of SREBP-2 and SCAP by in cells. The the of of SREBP-2 with SCAP. and cells experiments the cells with the of and of and and of the which of by Ref. G. Biol. PubMed Scopus Google Scholar). The of to by of either X. Sakai J. Brown M.S. Goldstein J.L. J. Biol. Chem. 1996; 271: Full Text Full Text PDF PubMed Scopus Google or cells in in the of the cells and to with The and from the of of cells to and with SREBP-2 or SCAP The to and of SCAP in cells. cells that express in with the cells with the with and cells and with in at and at with each at with in on at with and and in with at followed by at three with each P.A. Ho Y.K. Brown M.S. Goldstein J.L. J. Biol. PubMed Scopus Google Scholar). The at the of the of SREBP-2 and SCAP in ER membranes. The the between the COOH of the two both of which are the cytoplasm. The of SREBP-2 is by studies that protease (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google and of into the lumenal loop (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google Scholar, 9Duncan E.A. Brown M.S. Goldstein J.L. Sakai J. J. Biol. Chem. 1997; 272: 12778-12785Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar). The of the COOH terminus of SCAP on the cytosolic face of the membrane is on of 1) protease experiments to be J. J. and S. in 2) the of SCAP to HMG-CoA reductase, COOH-terminal domain faces the J. Brown M.S. Goldstein J.L. J. Biol. Chem. Full Text PDF PubMed Google Scholar, J. Biol. Chem. Full Text PDF PubMed Google Scholar, G. Goldstein J.L. Brown M.S. Cell. Full Text PDF PubMed Scopus Google Scholar); and 3) the in the that the COOH-terminal domain of SCAP with the COOH-terminal domain of SREBP-2, which is to face the (1Brown M.S. Goldstein J.L. Cell. 1997; 89: 331-340Abstract Full Text Full Text PDF PubMed Scopus (3002) Google Scholar). We show SCAP with membrane-spanning X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google by to HMG-CoA J. Biol. Chem. Full Text PDF PubMed Google we the and the terminus of SCAP be on either of the and of the of a to the of SCAP with and SREBP-2 in cells. to the the cells in which In cells the cleavage of SREBPs by of the HMG-CoA or by of cholesterol with which the cell with a SCAP. The complexes precipitated with and the and to and with or SREBP-2 The from the the forms of and SREBP-2 SREBP precipitated when a the of and we the with to that SCAP precipitated by the The from the SREBPs that with the of and the of the and by we that of the and of the SREBP-2 precipitated by The antibodies and the NH2-terminal and the NH2-terminal fragments of and which are in cell in the of fragments by with and by of the NH2-terminal fragments in the and precipitated with the The of revealed of the The of and that with SCAP of sterol or the of proteolytic sterols to regulate SREBP by the between SCAP and into the mechanism of the SCAP with SREBPs, we a of experiments in cells that to express forms of SREBPs or SCAP a of in which the cells with SCAP a of SREBP-2 with NH2-terminal of two of a from the herpes simplex precipitated with and with the on SREBP-2 when the cells with the we in the 1) or When cells only the SREBP-2 SCAP, the precipitated only a of SREBP-2 This on In when SCAP with SREBP-2, the precipitated of the SREBP-2 and of the with a that SCAP the This a in cells with the SCAP the of SCAP. We that SCAP stimulates cleavage of SREBPs X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). The in to requires the COOH-terminal The of the is on three 1) the NH2-terminal domain of SREBPs can be by the cleavage J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar); 2) of SREBPs at the COOH terminus and 3) of SCAP stimulates cleavage of SREBPs, and the of sterols X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). cells with a a form of SREBP-2 with the NH2-terminal The cells with sterols, and into the When the cells with a SCAP, cleavage of the protein and the in the When the COOH terminus of the protein at of SREBP-2, which to the of G. 1997; PubMed Scopus Google SCAP cleavage of the the of with in When the protein at which to the of SCAP proteolytic cleavage and The protein only amino acids the These that SCAP stimulates cleavage of SREBP-2 only when the COOH-terminal domain is that SCAP with SREBP-2 only when the COOH terminus is cells with a SCAP a the protein that at a to the COOH terminus of SREBP-2 or at the that in and the of the that are we the which cleavage at J. Duncan E.A. Rawson X. Brown M.S. Goldstein J.L. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). of the cell with and with the the at the terminus of the In the cells, of the with SCAP we only of the and of the is a control which that of SCAP present in three of the when the of antibodies In we precipitated with antibodies the protein and with only with the We conclude from that the of SCAP with SREBP-2 requires the COOH-terminal domain of the of SCAP with the COOH-terminal domain of SREBP-2, we cells with SCAP a of SREBP-2 that only the COOH-terminal domain In the of the we the COOH-terminal of SREBP-2 with or a COOH-terminal three of from a protein with and with the COOH-terminal domain of The COOH-terminal domain of SREBP-2 in the only when SCAP and with the COOH-terminal and that SCAP in the when the SCAP In of we the of precipitated with a of antibodies and the and with SCAP in the only when both that the SREBP-2 proteins precipitated by the antibodies the and that the COOH-terminal domain of SREBP-2 the with SCAP, we to the domain of SCAP that we cells with the the protein a the COOH-terminal domain of SCAP that with three of the the when SCAP with the the and SREBP-2 by with the the The protein only when the COOH terminus of SCAP of is a control that the precipitated the COOH-terminal of SCAP. the that the complexes the cells we a Two of cells with and two with in to from the two and the and the with The with the the and In the the in of cells that simultaneously with the SCAP and The that SCAP forms a complex with the form of SREBP-2 in cultured cells and that formation of complex with the of SCAP to stimulate cleavage of SREBP-2 at the Complex formation is by the COOH-terminal of SREBP-2 and SCAP, both of which are located on the cytosolic of the ER and nuclear envelope. The that the is cleavage is on the that of SREBP-2 at that or amino acids from the COOH terminus cleavage and simultaneously the of SCAP The between SREBP-2 and SCAP in with cells that express only the of proteins in of cells that both SCAP and SREBP-2 and The complex be precipitated with antibodies SCAP and 3) or with antibodies SREBP-2 The complex be precipitated when the cells only the COOH-terminal domain of either SCAP or SREBP-2 and that the COOH-terminal the We that the complex forms by between the COOH-terminal of SCAP and SREBP, we the that the two each with a protein that the We the that the domain of SCAP in the with SREBPs, domain is The of the COOH-terminal domain of SCAP in is with the in domain of at X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). These sequences to in proteins Lee Cell. 1995; Full Text PDF PubMed Scopus Google Scholar, J. A. 1996; PubMed Scopus Google and in in proteins T.F. PubMed Scopus Google Scholar). the occurs on the face of the to cleavage of SREBP-2 at on the lumenal of the SCAP to be a by its of to and by its to SREBPs in that the complex forms a a a active faces the lumen of the We are to of the complex to of We the of the complex the SREBP-2 is We that the COOH-terminal of SREBP-2 membrane-bound and is (8Hua X. Sakai J. Ho Y.K. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 29422-29427Abstract Full Text Full Text PDF PubMed Scopus (148) Google Scholar). is that SCAP with and is with SCAP by from the COOH-terminal which to SREBP In cells of the SREBP-2 with SCAP, and the in the We that of the SCAP in the cell from by a of SCAP from the In the SCAP is and the protein when we to to and in The of SREBP-2 that the of SCAP is in complex formation and that only of the SREBP are in a complex with SCAP at This is by the that of SCAP stimulates the cleavage of SREBPs X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google which that the of SCAP is We the that of the SREBPs are in a complex with SCAP, of the complexes or The of that the of complex is when SREBP-2 cleavage is by with or by with These that SCAP to sterols by from sterols SCAP to from the complex to The of that SREBP-2, is with SCAP. of the experiments with We experiments with SREBP-1a and that SREBP-1a forms a complex with SCAP and that the of complex is when the COOH-terminal domain of SREBP-1a is We that cells a form of which is in cleavage of SREBPs and which by sterols X. A. Goldstein J.L. Brown M.S. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). In experiments we that is with SREBP-2 to the SCAP in cells in the of the the of SREBPs and SCAP, that the complex a the The to the that SCAP is a required of the that to cleavage of SREBPs at are to and to of the complex to the We with the and with cultured cells, in the with and and and
Sakai et al. (Fri,) studied this question.