Open AccessTyrosine phosphorylation plays a role in increasing maspin protein levels and its cytoplasmic accumulation
Author(s) -
Tamazato Longhi Mariana,
Cella Nathalie
Publication year - 2012
Publication title -
febs open bio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.718
H-Index - 31
ISSN - 2211-5463
DOI - 10.1016/j.fob.2012.04.006
Subject(s) - maspin , protein tyrosine phosphatase , phosphorylation , tyrosine , western blot , cytoplasm , phosphatase , isoelectric focusing , subcellular localization , tyrosine phosphorylation , biochemistry , isoelectric point , protein phosphorylation , biology , chemistry , microbiology and biotechnology , enzyme , protein kinase a , cancer , genetics , metastasis , gene
Maspin is a tumor suppressor with many biological activities, multiple ligands and different subcellular localizations. Its underlying molecular mechanism remains elusive. We hypothesized that phosphorylation might regulate maspin localization and function. Using two‐dimensional gel electrophoresis with different focusing power followed by Western blot we identified four different maspin forms with the same molecular weight (42 kDa), but different isoelectric points. Three of these forms were sensitive to acidic phosphatase treatment, suggesting that they are phosphorylated. Sodium peroxidovanadate treatment, a protein‐tyrosine phosphatase inhibitor, resulted in a rapid increase in maspin protein levels and cytoplasmic accumulation. These data show that there are three different maspin tyrosine phosphoforms. Inhibition of tyrosine phosphatases increased maspin protein levels and leads to its cytoplasmic accumulation.