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.
Gruppuso
P A
PA
Department of Pediatrics, Brown University, Providence, RI.
Boylan
J M
JM
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