Abstract: Disclosed is an evaluation peptide for evaluating the efficiency of a pretreatment in the quantification of a protein using a mass spectrometer, having high reliability and high general versatility. Also disclosed is an artificial standard protein comprising the evaluation peptide. Further disclosed is a method for quantifying a protein utilizing the artificial standard protein. Specifically disclosed is a method for selecting a peptide which consists of an amino acid sequence not agreeing with that in a naturally occurring protein and a variant thereof and capable of being detected by mass spectrometry and which has an amino acid that can be recognized by a protein-digesting enzyme, and using the peptide as an evaluation peptide for use in the quantification of a protein by a mass spectrometer.

Abstract: An object of the present invention is to provide a method for producing a stable isotope-labeled target peptide fragment in mass spectrometry, which achieves inexpensive and convenient production.

Abstract: An object of the present invention is to provide a method for producing a stable isotope-labeled target peptide fragment in mass spectrometry, which achieves inexpensive and convenient production.

Abstract: Disclosed is an evaluation peptide for evaluating the efficiency of a pretreatment in the quantification of a protein using a mass spectrometer, having high reliability and high general versatility. Also disclosed is an artificial standard protein comprising the evaluation peptide. Further disclosed is a method for quantifying a protein utilizing the artificial standard protein. Specifically disclosed is a method for selecting a peptide which consists of an amino acid sequence not agreeing with that in a naturally occurring protein and a variant thereof and capable of being detected by mass spectrometry and which has an amino acid that can be recognized by a protein-digesting enzyme, and using the peptide as an evaluation peptide for use in the quantification of a protein by a mass spectrometer.

Abstract: There are provided a peptide consisting of an amino acid sequence for simultaneously quantifying absolute amounts of metabolizing enzyme proteins in a biological sample at high sensitivity and a method for using the same. A peptide which can be detected at high sensitivity with a mass spectrometer that enables highly sensitive simultaneous quantification of metabolizing enzymes, intracellular proteins, is selected, and the amino acid sequence thereof is identified. Using a stable-isotope-labeled peptide having the same amino acid sequence as the amino acid sequence of this peptide to be quantified, a mass spectrometry by LC-MS/MS is performed at predetermined concentration levels of the stable-isotope-labeled peptide to create a calibration curve.

Abstract: A method is provided for quantifying a plasma membrane protein present by using a stable-isotope labeled peptide as a probe by mass spectrometry in a simple, quick and accurate manner. A plasma membrane protein is fragmented to prepare an oligopeptide fragment, identified by LC/MS/MS. A subject peptide for quantification is selected if the peptide is obtained by fragmenting with a protease, the peptide is specific to a target molecule, and if the peptide has a high total score value based on selective criteria for hydrophobic amino acids content, sequence conditions, number of amino acid residues, specific amino acid sequence conditions, etc. According to these criteria, a subject peptide fragment that can be ionized by ESI method is selected. By using the subject peptide for and a stable-isotope labeled peptide, the plasma membrane protein is quantified accurately by mass spectrometry.

Abstract: To provide an immortalized capillary pericyte line which maintains the original function/property of the cell line-deriving tissue, its establishment method, and the screening method for useful substance using the immortalized capillary pericyte line. Cerebral tissue of a transgenic rat carrying the large T antigen gene of SV40 thermo-sensitive mutant line tsA58 is homogenized and the resultant brain capillaries are treated with protease, thus obtained brain capillary cells are subcultured to establish an immortalized cell that expresses SV40 thermo-sensitive large T antigen, PDGF receptor ?, and Angiopoietin-1. In addition, the immortalized vascular pericyte line has ability to deposit calcium on matrix by dense culture.

Abstract: To provide an immortalized capillary pericyte line which maintains the original function/property of the cell line-deriving tissue, its establishment method, and the screening method for useful substance using the immortalized capillary pericyte line. Cerebral tissue of a transgenic rat carrying the large T antigen gene of SV40 thermo-sensitive mutant line tsA58 is homogenized and the resultant brain capillaries are treated with protease, thus obtained brain capillary cells are subcultured to establish an immortalized cell that expresses SV40 thermo-sensitive large T antigen, PDGF receptor &bgr;, and Angiopoietin-1. In addition, the immortalized vascular pericyte line has ability to deposit calcium on matrix by dense culture.

Abstract: New peptides represented by the following general formula (wherein X is OH or NH2, R is an amino acid residue selected from Arg, His, Lys, Methyl-Arg or Methyl-Tyr, n is an integer of 1-4, and in the case that n is 2-4, R may be identical with or different from each other) and an anti-dementia drug which contains one or more of these new peptides and has a high blood brain barrier (BBB) permeability and furthermore is low in a side effect.

Abstract: Established cells derived from retinal capillary endothelial cells, choroid plexus epithelial cells, or brain capillary endothelial cells or a transgenic animal carrying a large T-antigen gene of an SV40 temperature sensitive mutant tsA58. The cell line derived from retinal capillary endothelial cells expresses a temperature sensitive SV40 large T-antigen, GLUT-1 transporter, and p-glycoprotein. The cell line derived from choroid plexus epithelial cells expresses a temperature sensitive SV40 large T-antigen gene and shows localization of Na+—K+ ATPase and GLUT-1 transporter in the cell membrane. When cultured in a monolayer, it shows the localization of Na+—K+ ATPase in the apical side. The cell line derived from brain capillary endothelial cells expresses a temperature sensitive SV40 large T-antigen, GLUT-1 transporter, p-glycoprotein, alkaline phosphatase, and &ggr;-glutamyltransferase.