The nontransmembrane tyrosine phosphatase PTP-1B localizes to the endoplasmic reticulum via its 35 amino acid C-terminal sequence.
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Frangioni JV, Beahm PH, Shifrin V, Jost CA, Neel BG
The nontransmembrane tyrosine phosphatase PTP-1B localizes to the endoplasmic reticulum via its 35 amino acid C-terminal sequence.
Cell. 1992 Feb 7;68(3):545-60.
- PubMed ID
- 1739967 [ View in PubMed]
- Abstract
We report the first intracellular characterization of an endogenous nontransmembrane protein tyrosine phosphatase (PTP). Using affinity-purified polyclonal antibodies, we have identified PTP-1B as a 50 kd serine phosphoprotein in immunoprecipitation and immunoblotting assays. Surprisingly, indirect immunofluorescence experiments indicate that PTP-1B is localized predominantly in the endoplasmic reticulum (ER). Subcellular fractionation is consistent with this localization and establishes that PTP-1B is tightly associated with microsomal membranes, with its phosphatase domain oriented towards the cytoplasm. The C-terminal 35 amino acids of PTP-1B are both necessary and sufficient for targeting to the ER. The finding of a tyrosine phosphatase on the ER suggests new possibilities for cellular events controlled by tyrosine phosphorylation.