The Phox Homology (PX) Domain

2018 ◽  
pp. 1-17 ◽  
Author(s):  
Mintu Chandra ◽  
Brett M. Collins
Keyword(s):  
Px Domain ◽  
Phox Homology

scholarly journals Determinants of the Endosomal Localization of Sorting Nexin 1

2005 ◽  
Vol 16 (4) ◽  
pp. 2049-2057 ◽  
Author(s):  
Qi Zhong ◽  
Martin J. Watson ◽  
Cheri S. Lazar ◽  
Andrea M. Hounslow ◽  
Jonathan P. Waltho ◽  
...  
Keyword(s):  
Binding Pocket ◽  
Early Endosome ◽  
Nmr Structure ◽  
Sorting Nexin ◽  
High Affinity ◽  
Terminal Domain ◽  
Px Domain ◽  
Phox Homology ◽  
Phosphatidylinositol 3

The sorting nexin (SNX) family of proteins is characterized by sequence-related phox homology (PX) domains. A minority of PX domains bind with high affinity to phosphatidylinositol 3-phosphate [PI(3)P], whereas the majority of PX domains exhibit low affinity that is insufficient to target them to vesicles. SNX1 is located on endosomes, but its low affinity PX domain fails to localize in vivo. The NMR structure of the PX domain of SNX1 reveals an overall fold that is similar to high-affinity PX domains. However, the phosphatidylinositol (PI) binding pocket of the SNX1 PX domain is incomplete; regions of the pocket that are well defined in high-affinity PX domains are highly mobile in SNX1. Some of this mobility is lost upon binding PI(3)P. The C-terminal domain of SNX1 is a long helical dimer that localizes to vesicles but not to the early endosome antigen-1–containing vesicles where endogenous SNX1 resides. Thus, the obligate dimerization of SNX1 that is driven by the C-terminal domain creates a high-affinity PI binding species that properly targets the holo protein to endosomes.

scholarly journals Regulation of phospholipase D1 subcellular cycling through coordination of multiple membrane association motifs

2003 ◽  
Vol 162 (2) ◽  
pp. 305-315 ◽  
Author(s):  
Guangwei Du ◽  
Yelena M. Altshuller ◽  
Nicolas Vitale ◽  
Ping Huang ◽  
Sylvette Chasserot-Golaz ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Vesicle ◽  
Membrane Association ◽  
Ph Domain ◽  
Px Domain ◽  
Ph Domains ◽  
Phospholipase D1 ◽  
And Function ◽  
Phox Homology ◽  
Cellular Stimulation

The signaling enzyme phospholipase D1 (PLD1) facilitates membrane vesicle trafficking. Here, we explore how PLD1 subcellular localization is regulated via Phox homology (PX) and pleckstrin homology (PH) domains and a PI4,5P2-binding site critical for its activation. PLD1 localized to perinuclear endosomes and Golgi in COS-7 cells, but on cellular stimulation, translocated to the plasma membrane in an activity-facilitated manner and then returned to the endosomes. The PI4,5P2-interacting site sufficed to mediate outward translocation and association with the plasma membrane. However, in the absence of PX and PH domains, PLD1 was unable to return efficiently to the endosomes. The PX and PH domains appear to facilitate internalization at different steps. The PH domain drives PLD1 entry into lipid rafts, which we show to be a step critical for internalization. In contrast, the PX domain appears to mediate binding to PI5P, a lipid newly recognized to accumulate in endocytosing vesicles. Finally, we show that the PH domain–dependent translocation step, but not the PX domain, is required for PLD1 to function in regulated exocytosis in PC12 cells. We propose that PLD1 localization and function involves regulated and continual cycling through a succession of subcellular sites, mediated by successive combinations of membrane association interactions.

The Phox homology (PX) domain, a new player in phosphoinositide signalling

2001 ◽  
Vol 360 (3) ◽  
pp. 513-530 ◽  
Author(s):  
Yue XU ◽  
Li-Fong SEET ◽  
Brendon HANSON ◽  
Wanjin HONG
Keyword(s):  
Ph Domain ◽  
Pleckstrin Homology ◽  
Structural Motifs ◽  
Cellular Processes ◽  
Enth Domain ◽  
Fyve Domain ◽  
Cellular Events ◽  
Px Domain ◽  
Phox Homology ◽  
Recent Establishment

Phosphoinositides are key regulators of diverse cellular processes. The pleckstrin homology (PH) domain mediates the action of PtdIns(3,4)P2, PtdIns(4,5)P2 and PtdIns(3,4,5)P3, while the FYVE domain relays the pulse of PtdIns3P. The recent establishment that the Phox homology (PX) domain interacts with PtdIns3P and other phosphoinositides suggests another mechanism by which phosphoinositides can regulate/integrate multiple cellular events via a spectrum of PX domain-containing proteins. Together with the recent discovery that the epsin N-terminal homologue (ENTH) domain interacts with PtdIns(4,5)P2, it is becoming clear that phosphoinositides regulate diverse cellular events through interactions with several distinct structural motifs present in many different proteins.

scholarly journals The Phox homology (PX) domain, a new player in phosphoinositide signalling

2001 ◽  
Vol 360 (3) ◽  
pp. 513 ◽  
Author(s):  
Yue XU ◽  
Li-Fong SEET ◽  
Brendon HANSON ◽  
Wanjin HONG
Keyword(s):  
Px Domain ◽  
Phox Homology

scholarly journals SNX27 mediates PDZ-directed sorting from endosomes to the plasma membrane

2010 ◽  
Vol 190 (4) ◽  
pp. 565-574 ◽  
Author(s):  
Benjamin E.L. Lauffer ◽  
Cristina Melero ◽  
Paul Temkin ◽  
Cai Lei ◽  
Wanjin Hong ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Pdz Domain ◽  
Cis Acting ◽  
Sorting Nexin ◽  
Px Domain ◽  
Early Endosomes ◽  
Discs Large ◽  
Protein Scaffolding ◽  
Phox Homology

Postsynaptic density 95/discs large/zonus occludens-1 (PDZ) domain–interacting motifs, in addition to their well-established roles in protein scaffolding at the cell surface, are proposed to act as cis-acting determinants directing the molecular sorting of transmembrane cargo from endosomes to the plasma membrane. This hypothesis requires the existence of a specific trans-acting PDZ protein that mediates the proposed sorting operation in the endosome membrane. Here, we show that sorting nexin 27 (SNX27) is required for efficient PDZ-directed recycling of the β2-adrenoreceptor (β2AR) from early endosomes. SNX27 mediates this sorting function when expressed at endogenous levels, and its recycling activity requires both PDZ domain–dependent recognition of the β2AR cytoplasmic tail and Phox homology (PX) domain–dependent association with the endosome membrane. These results identify a discrete role of SNX27 in PDZ-directed recycling of a physiologically important signaling receptor, and extend the concept of cargo-specific molecular sorting in the recycling pathway.

Phospholipase D1 and potential targets of its hydrolysis product, phosphatidic acid

2003 ◽  
Vol 31 (1) ◽  
pp. 94-97 ◽  
Author(s):  
N.T. Ktistakis ◽  
C. Delon ◽  
M. Manifava ◽  
E. Wood ◽  
I. Ganley ◽  
...  
Keyword(s):  
Phosphatidic Acid ◽  
Hydrolysis Product ◽  
Ph Domain ◽  
Novel Proteins ◽  
Fatty Acylation ◽  
Px Domain ◽  
Phospholipase D1 ◽  
Sphingosine 1 Phosphate ◽  
Phox Homology ◽  
Adp Ribosylation Factor

Phospholipase D (PLD) hydrolyses phosphatidylcholine into phosphatidic acid (PA) and choline. Our work aims to understand the properties of PLD1, and to identify downstream targets of PA. In one set of projects, we have focused on membrane-targeting mechanisms and have proposed a hierarchy of signals that allows PLD1 to localize to intracellular membranes. These signals involve a functional pleckstrin homology (PH) domain and its fatty acylation on two adjacent cysteine residues. A nearby Phox homology (PX) domain may modulate the function of the fatty acylated PH domain. This complex array of signals is probably necessitated by the targeting of PLD1 to multiple endocytic and secretory membranes under basal and signal-dependent conditions. In another set of projects, we have used chemically synthesized PA coupled to a solid support in order to identify proteins that interact with this phospholipid. Several proteins have emerged from this screen as potential targets. Some (e.g. ADP-ribosylation factor, coatomer β subunit) are involved in trafficking and their PA affinity can be understood in terms of their regulated cycling on and off membranes during rounds of transport. Others (sphingosine 1-phosphate kinase and PtdIns4P 5-kinase) are implicated in pathways that also involve PLD activation. Others still are novel proteins (brain-specific neurochondrin) whose affinity for PA may contribute to an understanding of their cellular function.

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