1. A fragment of a cDNA molecule, comprising nucleotides 202-807 of the sequence SEQ ID NO:1, provided in the List of sequences, encoding a beta-amyloid peptide binding protein (BBP) fragment comprising amino acids 68-269 of SEQ ID NO:2, provided in said List, and also a variant of said cDNA fragment, obtained on the basis of degeneracy of the genetic code. 2. A fragment of a cDNA molecule according to claim 1, which is an insert of clone pEK 196 ATCC 98399. 3. A cDNA molecule having a nucleotide sequence SEQ ID NO:1, provided in the List of sequences, encoding a beta-amyloid peptide-binding protein (BBP) having an amino acid sequence of SEQ ID NO:2 provided in said List and also a variant of said cDNA molecule prepared on the basis of degeneracy of the genetic code. 4. A cDNA molecule according to claim 3, which is an insert of clone BBP1-f1 ATCC 98617. 5. A polynucleotide which hybridizes under stringent conditions to a cDNA molecule according to any one of claims 1-4 or the complementary molecule thereof, wherein said polynucleotide has at least 75% of the length of any one of said cDNA molecules and encodes a beta-amyloid peptide. 6. A probe or primer comprising a nucleotide sequence capable of hybridizing to nucleotides 172-194 of the cDNA molecule according to claim 3. 7. A polynucleotide comprising at least one expression control sequence operably linked to at least one polynucleotide selected from the group consisting of the cDNA molecule of claims 1 to 4. 8. A host cell strain transformed with the polynucleotide of claim 7 wherein said cell is a prokaryotic cell. 9. A host cell strain transformed with the polynucleotide of claim 7 wherein said cell is an eukaryotic cell. 10. A beta-amyloid peptide binding protein (BBP) fragment comprising amino acids 68-269 of SEQ ID NO:2 provided in the List of sequences encoded by a fragment of a cDNA molecule comprising nucleotides 202-807 of SEQ ID NO:1, provided in said List or is encoded by a variant of said cDNA fragment, obtained on the basis of degeneracy of the genetic code. 11. A beta-amyloid peptide binding protein (BBP) fragment encoded by a fragment of a cDNA molecule according to claim 1 which is an insert of clone pEK 196 ATCC 98399. 12. A beta-amyloid peptide binding protein (BBP) having an amino acid sequence of SEQ ID NO:2 provided in the List of sequences encoded by a cDNA molecule having a nucleotide sequence SEQ ID NO: 1 provided in said List or encoded by a variant of said cDNA molecule obtained on the basis of the degeneracy of the genetic code. 13. A protein BBP comprising an amino acid sequence encoded by a cDNA molecule according to claim 3, which is an insert of clone BBP1-f1 ATCC 98617. 14. A process for producing a protein according to any one of claims 12-13 or protein fragment according to any one of claims 10-11 comprising the steps of growing the host cell strain of claim 8 or 9 in appropriate culture medium and purifying the protein or a fragment thereof produced by said strain. 15. A protein produced according to the process of claim 14. 16. A fusion protein BBP comprising a protein according to any one of claims 12-13, 15 or protein fragment according to any one of claims 10-11 linked to a heterologous protein or peptide sequence. 17. An oligonucleotide being a BBP1 gene expression inhibitor comprising nucleotide sequence consisting of 15 to 35 nucleotides wherein said nucleotide sequence hybridizes under stringent conditions to a cDNA molecule according to any one of claims 1 to 4. 18. A method for determining the quantity of a polynucleotide encoding a beta-amyloid peptide-binding protein (BBP) in a sample comprising the steps of: (a) hybridizing to a sample a probe according to claim 6 under stringent conditions; and (b) determining the quantity of said probe bound to polynucleotides in the sample. 19. An antibody which binds specifically, to an extracellular region of a protein according to any one of claims 12-13, 15-16 or protein fragment according to any one of claims 10-11. 20. A method for detecting in a sample the quantity of a protein according to any one of claims 12-13, 15-16 or protein fragment according to any one of claims 10-11 comprising the steps of: a) incubating with a sample and a control, said control comprising varying amounts of known BBP protein or BBP protein fragment, an antibody according to claim 19 wherein said antibody is linked to a reporter molecule; b) determining the quantity of said antibody bound to said BBP protein or protein fragment in the sample; and c) calculating the quantity of said BBP protein or BBP protein fragment by comparing the quantity of antibody in b) to said controls. 21. A method for the treatment of a patient having need to inhibit beta-amyloid peptide accumulation in the brain comprising administering to the patient a therapeutically effective amount of a protein according to any one of claims 12-13, 15-16 or protein fragment according to any one of claims 10-11.