Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:2.5.1.18 (
glutathione S-transferase
)
22,582
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
PtdIns(3,4) P (2), a breakdown product of the lipid second messenger PtdIns(3,4,5) P (3), is a key signalling molecule in pathways controlling various cellular events. Cellular levels of PtdIns(3,4) P (2) are elevated upon agonist stimulation, mediating downstream signalling pathways by recruiting proteins containing specialized lipid-binding modules, such as the pleckstrin homology (PH) domain. A recently identified protein,
TAPP1
(tandem-PH-domain-containing protein 1), has been shown to interact in vitro with high affinity and specificity with PtdIns(3,4) P (2) through its C-terminal PH domain. In the present study, we have utilized this PH domain tagged with
glutathione S-transferase
(
GST
-
TAPP1
-PH) as a probe in an on-section immunoelectron microscopy labelling procedure, mapping the subcellular distribution of PtdIns(3,4) P (2). As expected, we found accumulation of PtdIns(3,4) P (2) at the plasma membrane in response to the agonists platelet-derived growth factor and hydrogen peroxide. Importantly, however, we also found agonist stimulated PtdIns(3,4) P (2) labelling of intracellular organelles, including the endoplasmic reticulum and multivesicular endosomes. Expression of the 3-phosphatase PTEN (phosphatase and tensin homologue deleted on chromosome 10) in PTEN-null U87MG cells revealed differential sensitivity of these lipid pools to the enzyme. These data suggest a role for PtdIns(3,4) P (2) in endomembrane function.
...
PMID:Detection of novel intracellular agonist responsive pools of phosphatidylinositol 3,4-bisphosphate using the TAPP1 pleckstrin homology domain in immunoelectron microscopy. 1460 33
Phosphatidylinositol 3,4-bisphosphate [PtdIns(3,4)P
2
] is a phosphoinositide that plays important roles in signal transduction, endocytosis, and cell migration among others. The intracellular distribution of PtdIns(3,4)P
2
has mainly been studied by observing the distribution of GFP-tagged PtdIns(3,4)P
2
-binding protein domains in live cells and by labeling with anti-PtdIns(3,4)P
2
antibody in fixed cell samples, but these methods only offer low spatial resolution results and may have pitfalls. In the present study, we developed an electron microscopic method to observe the PtdIns(3,4)P
2
distribution using the SDS-treated freeze-fracture replica labeling method. The recombinant
GST
-tagged pleckstrin homology (PH) domain of
TAPP1
was used as the binding probe, and its binding to PtdIns(3,4)P
2
in the freeze-fracture replica was confirmed by using liposomes containing different phosphoinositides and by the lack of labeling by a mutant probe, in which one amino acid in the PH domain was substituted. The method was applied to NIH3T3 cell samples and showed that the increase of PtdIns(3,4)P
2
in cells treated with hydrogen peroxide occurs in the cytoplasmic leaflet of the plasma membrane, except in the caveolar membrane. The present method can define the distribution of PtdIns(3,4)P
2
at a high spatial resolution and will facilitate our understanding of the physiological function of this less studied phosphoinositide.
...
PMID:A New Electron Microscopic Method to Observe the Distribution of Phosphatidylinositol 3,4-bisphosphate. 2927 16
