The gene encoding DRAP (BACE2), a glycosylated transmembrane protein of the aspartic protease family, maps to the down critical region.
We applied cDNA selection methods to a genomic clone (YAC 761B5) from chromosome 21 located in the so-called 'Down critical region' in 21q22.3. Starting from human fetal heart and brain mRNAs we obtained and sequenced several cDNA clones. One of these clones (Down region aspartic protease (DRAP), named also BACE2 according to the gene nomenclature) revealed a striking nucleotide and amino acid sequence identity with several motifs present in members of the aspartic protease family. In particular the amino acid sequences comprising the two catalytic sites found in all mammalian aspartic proteases are perfectly conserved. Interestingly, the predicted protein shows a typical membrane spanning region; this is at variance with most other known aspartic proteases, which are soluble molecules. We present preliminary evidence, on the basis of in vitro translation studies and cell transfection, that this gene encodes a glycosylated protein which localizes mainly intracellularly but to some extent also to the plasma membrane. Furthermore DRAP/BACE2 shares a high homology with a newly described beta-secretase enzyme (BACE-1) which is a transmembrane aspartic protease. The implications of this finding for Down syndrome are discussed.
Acquati
F
F
Dipartimento Biologia Strutturale e Funzionale, Universita' Insubria, via Dunant 3, Varese, Italy.
Accarino
M
M
Nucci
C
C
Fumagalli
P
P
Jovine
L
L
Ottolenghi
S
S
Taramelli
R
R
D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D002474:Cell-Free System / Q000378:metabolism; D002874:Chromosome Mapping; D018244:Chromosomes, Artificial, Yeast / Q000235:genetics; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D004314:Down Syndrome / Q000235:genetics*; D010450:Endopeptidases; D006023:Glycoproteins / Q000235:genetics*; D006031:Glycosylation; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D006023:Glycoproteins; D008565:Membrane Proteins; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509284:BACE2 protein, human; C509280:BACE1 protein, human; C509282:Bace1 protein, mouse