Memapsin 2 (beta-secretase) cytosolic domain binds to the VHS domains of GGA1 and GGA2: implications on the endocytosis mechanism of memapsin 2.
Memapsin 2, or beta-secretase, is a membrane-anchored aspartic protease that initiates the cleavage of beta-amyloid precursor protein (APP) leading to the production of beta-amyloid peptide in the brain and the onset of Alzheimer's disease. Memapsin 2 and APP are both endocytosed into endosomes for cleavage. Here we show that the cytosolic domain of memapsin 2, but not that of memapsin 1, binds the VHS domains of GGA1 and GGA2. Gel-immobilized VHS domains of GGA1 and GGA2 also bound to full-length memapsin 2 from cell mammalian lysates. Mutagenesis studies established that Asp(496), Leu(499) and Leu(500) were essential for the binding. The spacing of these three residues in memapsin 2 is identical to those in the cytosolic domains of mannose-6-phosphate receptors, sortilin and low density lipoprotein receptor-related protein 3. These observations suggest that the endocytosis and intracellular transport of memapsin 2, mediated by its cytosolic domain, may involve the binding of GGA1 and GGA2.
Protein Studies Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
Xiangyuan
X
He
Wan-Pin
WP
Chang
Gerald
G
Koelsch
Jordan
J
Tang
D020727:ADP-Ribosylation Factors / Q000737:chemistry / Q000378:metabolism*; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D003001:Cloning, Molecular; D003600:Cytosol / Q000378:metabolism*; D018076:DNA, Complementary; D004705:Endocytosis; D010450:Endopeptidases; D006801:Humans; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D018076:DNA, Complementary; C407306:GGA adaptor proteins; C405944:GGA2 protein, human; D011506:Proteins; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509284:BACE2 protein, human; C509280:BACE1 protein, human; D020727:ADP-Ribosylation Factors