Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.5.1.18 (glutathione S-transferase)
 22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Degradation or "down-regulation" of protease-activated receptor-1 (PAR1), a G protein-coupled receptor for thrombin, is critical for termination of receptor signaling. Toward understanding the molecular mechanisms by which activated PAR1 is internalized, sorted to lysosomes, and degraded, we investigated whether PAR1 interacted with sorting nexin 1 (SNX1). SNX1 is a membrane-associated protein that functions in lysosomal sorting of the epidermal growth factor receptor. In vitro biochemical binding assays revealed a specific interaction between a glutathione S-transferase fusion of SNX1 and PAR1. In HeLa cells, activated PAR1 colocalized with endogenous SNX1 and coimmunoprecipitated SNX1. SNX1 contains a phox homology domain predicted to bind phosphatidylinositol-3-phosphate and a C-terminal coiled-coil region. To assess SNX1 function, we examined the effects of SNX1 deletion mutants on PAR1 trafficking. Neither the N terminus nor phox homology domain of SNX1 affected PAR1 trafficking. By contrast, overexpression of SNX1 C-terminal domain markedly inhibited agonist-induced degradation of PAR1, whereas internalization remained virtually intact. Immunofluorescence microscopy studies revealed substantial PAR1 accumulation in an early endosome antigen-1-positive compartment in agonist-treated cells expressing SNX1 C terminus. By contrast, lysosome-associated membrane protein-1 distribution was unperturbed. Together, these findings strongly suggest a role for SNX1 in sorting of PAR1 from early endosomes to lysosomes. Moreover, this study provides the first example of a protein involved in lysosomal sorting of a G protein-coupled receptor in mammalian cells.
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PMID:Down-regulation of protease-activated receptor-1 is regulated by sorting nexin 1. 1205 63

The mechanisms underlying targeted sorting of endocytosed receptors for recycling to the plasma membrane or degradation in lysosomes are poorly understood. In this report, the C-terminal tails of the five dopamine receptors (D1-D5) were expressed as glutathione S-transferase (GST) fusion proteins and studied for their interaction with ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50) and N-ethylmaleimide-sensitive factor (NSF), which are known to be involved in post-endocytic recycling of receptors back to the plasma membrane, and with sorting nexin 1 (SNX1), known to be involved in targeting receptors to lysosomal degradation. EBP50 did not bind any of the dopamine receptor tails. NSF bound strongly to D1 and D5 and only weakly to D2, D3 and D4. However, SNX1 clearly distinguished between D1 and D5, as only D5 bound strongly to this protein. This report shows that there are distinct interaction patterns for NSF and SNX1 to the various dopamine receptor subtypes.
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PMID:Distinct in vitro interaction pattern of dopamine receptor subtypes with adaptor proteins involved in post-endocytotic receptor targeting. 1470 63

Adaptor and scaffolding proteins determine the cellular targeting, the spatial, and thereby the functional association of G protein-coupled seven-transmembrane receptors with co-receptors, transducers, and downstream effectors and the adaptors determine post-signaling events such as receptor sequestration through interactions, mainly with the C-terminal intracellular tails of the receptors. A library of tails from 59 representative members of the super family of seven-transmembrane receptors was probed as glutathione S-transferase fusion proteins for interactions with four different adaptor proteins previously proposed to be involved in post-endocytotic sorting of receptors. Of the two proteins suggested to target receptors for recycling to the cell membrane, which is the route believed to be taken by a majority of receptors, ERM (ezrin-radixin-moesin)-binding phosphoprotein 50 (EBP50) bound only a single receptor tail, i.e. the beta(2)-adrenergic receptor, whereas N-ethylmaleimide-sensitive factor bound 11 of the tail-fusion proteins. Of the two proteins proposed to target receptors for lysosomal degradation, sorting nexin 1 (SNX1) bound 10 and the C-terminal domain of G protein-coupled receptor-associated sorting protein bound 23 of the 59 tail proteins. Surface plasmon resonance analysis of the binding kinetics of selected hits from the glutathione S-transferase pull-down experiments, i.e. the tails of the virally encoded receptor US28 and the delta-opioid receptor, confirmed the expected nanomolar affinities for interaction with SNX1. Truncations of the NK(1) receptor revealed that an extended binding epitope is responsible for the interaction with both SNX1 and G protein-coupled receptor-associated sorting protein as well as with N-ethylmaleimide-sensitive factor. It is concluded that the tail library provides useful information on the general importance of certain adaptor proteins, for example, in this case, ruling out EBP50 as being a broad spectrum-recycling adaptor.
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PMID:A library of 7TM receptor C-terminal tails. Interactions with the proposed post-endocytic sorting proteins ERM-binding phosphoprotein 50 (EBP50), N-ethylmaleimide-sensitive factor (NSF), sorting nexin 1 (SNX1), and G protein-coupled receptor-associated sorting protein (GASP). 1545 21