Phox homology domain (PX domain)

The **Phox homology (PX) domain** is a conserved phospholipid-binding protein domain of about 120 amino acids present in more than 250 proteins across eukaryotic species[1][5][6]. It functions as a membrane-interacting module that binds specifically to phosphoinositide lipids, most commonly phosphatidylinositol 3-phosphate (PtdIns(3)P), which marks organelle identity in the endocytic system[1][3][5]. PX domains are found in proteins such as sorting nexins (SNX), NADPH oxidase subunits (p40phox, p47phox), phospholipases D1/D2, and kinases like PI3K and CISK[1][5]. PX domain-containing proteins are implicated in diverse cellular functions, including protein sorting, vesicular trafficking, membrane remodeling, phospholipid metabolism, and cell signaling[1][3][5][7]. Dysregulation or mutation of PX domain proteins has been linked to diseases, notably some cancers, Alzheimer’s disease (due to roles in amyloid production), and pathogenic invasions[5]. The PX domain itself is not a single therapeutic target but a structural motif present in many different proteins, some of which may be drug targets or therapeutic points of interest[1][5][3]. **Note:** "PX domains" refers to a structural domain found within many distinct proteins, not to a specific target molecule such as a receptor or enzyme; thus, it is not considered a standalone therapeutic target, and referring to "PX domains" as a target is incorrect[1][5].

Other names

Phox homology regionPhox domain