title: Isoenzyme pattern and partial characterization of hexosaminidases in the membrane and cytosol of human erythrocytes.
abstract: OBJECTIVE
  Hexosaminidase activity is present in lysosomes, plasma membrane and cytosol of many human cells. Plasma membrane and cytosolic hexosaminidase is not well characterized, particularly as regards their isoenzyme forms and their relationship with the lysosomal ones.
  
  
  METHODS
  Erythrocyte hexosaminidase isoforms were chromatographically separated, characterized and compared to those in the plasma of healthy individuals and in the erythrocytes of a Tay-Sachs patient.
  
  
  RESULTS
  Hexosaminidase isoenzymes were found in plasma membrane and cytosol and were composed of the same alpha- and beta-subunits as the lysosomal and plasma hexosaminidase A and B isoenzymes, though with some structural and kinetic differences. In addition, the cytosol contained a hexosaminidase that is a specific N-acetyl-beta-D-glucosaminidase, the one involved in the removal of N-acetylglucosamine residues O-linked to proteins, named O-GlcNAcase.
  
  
  CONCLUSIONS
  This work provides an additional step in the characterization of hexosaminidases helping better understand their role in non-lysosomal compartments and their involvement in physiological or pathological situations.
authors.affiliation: Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, School of Medicine, Via Saldini, 50-20133 Milan, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Massaccesi
authors.forename: Adriana
authors.initials: A
authors.lastname: Lombardo
authors.forename: Bruno
authors.initials: B
authors.lastname: Venerando
authors.forename: Guido
authors.initials: G
authors.lastname: Tettamanti
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Goi
mesh_terms: D000328:Adult; D002852:Chromatography, Ion Exchange; D002853:Chromatography, Liquid; D003600:Cytosol / Q000201:enzymology*; D004910:Erythrocyte Membrane / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D054818:Hexosaminidase A; D006596:Hexosaminidases / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013661:Tay-Sachs Disease / Q000201:enzymology; D001619:beta-N-Acetylhexosaminidases / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D006596:Hexosaminidases; D054818:Hexosaminidase A; D001619:beta-N-Acetylhexosaminidases