Multiple dual specificity protein tyrosine phosphatases are expressed and regulated differentially in liver cell lines.

An emerging subclass of protein-tyrosine phosphatases (PTPases) exhibits sequence identity to the vaccinia H-1 (VH-1) gene product. These VH-1-like PTPases possess the canonical HCXAGXXR(S/T) sequence common to all PTPases, but unlike other PTPases they exhibit dual catalytic activity toward phosphotyrosine and nearby phosphothreonine residues in substrate proteins. We have isolated ...
a novel VH-1-like PTPase, hVH-3, from the human placenta and compared various aspects of its expression with previously isolated members of this subfamily. The mammalian members of this subfamily including hVH-3 commonly localize to the nucleus and exhibit catalytic activity toward phosphorylated extracellular signal-regulated kinase. However, while the expression of some VH-1-like PTPases is extremely transient and independent of protein synthesis, hVH-3 expression is sustained over 3 h after being cell stimulated. Tissue-specific expression of hVH-3 is also distinct from other VH-1-like PTPases. Although VH-1-like PTPases have overlapping substrate specificity, there are differences in their mRNA regulation, response to extracellular stimuli, and tissue-specific expression, suggesting they serve specific roles in cellular function.
Mesh Terms:
Amino Acid Sequence, Animals, Base Sequence, Cloning, Molecular, DNA, Gene Expression Regulation, Enzymologic, Liver, Molecular Sequence Data, Protein Tyrosine Phosphatases, RNA, Messenger, Sequence Homology, Amino Acid, Substrate Specificity, Tumor Cells, Cultured
J. Biol. Chem.
Date: Jan. 20, 1995
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