title: The major protein of GLUT4-containing vesicles, gp160, has aminopeptidase activity.
abstract: A glycoprotein of M(r) 160,000 (gp160) represents the major protein component of GLUT4-containing vesicles other than GLUT4 itself. These vesicles are the tissue-specific secretory-like microsomal structures that are responsible for insulin-dependent translocation of GLUT4 to the cell surface in fat and muscle cells. Our previous studies demonstrated that the expression of gp160 is also limited to fat and muscle tissues, where it is localized exclusively in GLUT4-containing vesicles, and thus, it represents a marker protein for insulin-activated glucose transport. We demonstrate here that gp160 has structural homology to aminopeptidase N and possesses aminopeptidase activity in vitro. Since aminopeptidase activity has also been found in a variety of secretory type vesicles from other tissues, it may be essential for the organization and functioning of secretory machinery in different cell types.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118.
authors.forename: K V
authors.initials: KV
authors.lastname: Kandror
authors.forename: L
authors.initials: L
authors.lastname: Yu
authors.forename: P F
authors.initials: PF
authors.lastname: Pilch
mesh_terms: D017667:Adipocytes / Q000201:enzymology / Q000378:metabolism; D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000378:metabolism*; D000818:Animals; D018826:CD13 Antigens / Q000737:chemistry / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D009132:Muscles / Q000201:enzymology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017386:Sequence Homology, Amino Acid
chemical_list: D051275:Glucose Transporter Type 4; D008562:Membrane Glycoproteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495692:SLC2A4 protein, human; C495694:Slc2a4 protein, rat; D000626:Aminopeptidases; C097037:GLUT4-associated glycoprotein gp160, rat; D018826:CD13 Antigens