Heterogeneity of hepatic protein tyrosine phosphatases.
We have identified multiple members of the protein tyrosine phosphatase family in three subcellular compartments from rat liver; membrane, cytoskeleton and cytosol. Characterization based on substrate specificity, size, and reactivity with an anti-peptide antiserum against human placental PTP1B indicate the presence of at least three PTPases in Triton X-100 extracts of particulate membranes. Of these, one of 600 kDa possesses characteristics of a transmembrane, receptor-like enzyme. A fourth particulate PTPase (70 kDa) represents a distinct cytoskeletal PTPase. Cytosol contains one main PTPase species which was detected as a 41 kDa protein in Western immunoblots. These data indicate the existence of multiple hepatic PTPases whose differences in structure and subcellular localization may reflect functional heterogeneity.
Department of Pediatrics, Brown University, Providence, RI.
P A
PA
Gruppuso
J M
JM
Boylan
D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000201:enzymology; D002850:Chromatography, Gel; D003599:Cytoskeleton / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D007527:Isoenzymes / Q000032:analysis*; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D017027:Protein Tyrosine Phosphatases / Q000032:analysis*; D051381:Rats; D013379:Substrate Specificity
D007527:Isoenzymes; D017027:Protein Tyrosine Phosphatases