{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nPHETA1 (also known as IPIP27A or Ses1) functions as a critical endocytic adaptor by binding to inositol polyphosphate 5‐phosphatases such as OCRL1 and its homolog Inpp5b. Biochemical studies revealed that PHETA1 interacts with the C-terminal region of these phosphatases via a conserved motif reminiscent of that in the signaling protein APPL1. This interaction is necessary for proper receptor recycling from early and recycling endosomes to both the trans-Golgi network and the plasma membrane, which, when disrupted, may contribute to the pathology of disorders such as Lowe syndrome and Dent disease."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "PHETA1’s binding to OCRL is further elucidated by its interaction with the enzyme’s ASH-RhoGAP-like domain through a specific phenylalanine and histidine (F&H) motif. This binding event, which is mutually exclusive with that of APPL1, has been shown to depend on a short conserved amino acid sequence and is disrupted by particular missense mutations. These findings highlight PHETA1’s role in modulating discrete steps of the endocytic pathway, thereby underscoring the multifaceted mechanisms through which perturbations in OCRL-associated processes can lead to complex clinical manifestations."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": "In vivo studies using the zebrafish model further establish that PHETA1 (together with its homolog PHETA2) is essential for normal endocytic function, ciliogenesis in renal tissues, and craniofacial development. Disruption of pheta1/2 resulted in impaired endocytosis, abnormal ciliogenesis, reduced jaw size, and delayed chondrocyte differentiation. This developmental dysregulation was linked to altered cathepsin K activity and consequent accumulation of immature extracellular matrix components. Moreover, a patient-specific PHETA1 variant (R6C) exacerbated these craniofacial deficits in zebrafish, suggesting that the mutation exerts a dominant-negative effect and highlighting its potential contribution to disease pathogenesis."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": ""}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Christopher J Noakes, Grace Lee, Martin Lowe "}, {"type": "b", "children": [{"type": "t", "text": "The PH domain proteins IPIP27A and B link OCRL1 to receptor recycling in the endocytic pathway."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Mol Biol Cell (2011)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1091/mbc.E10-08-0730"}], "href": "https://doi.org/10.1091/mbc.E10-08-0730"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "21233288"}], "href": "https://pubmed.ncbi.nlm.nih.gov/21233288"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Laura E Swan, Livia Tomasini, Michelle Pirruccello, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Two closely related endocytic proteins that share a common OCRL-binding motif with APPL1."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Proc Natl Acad Sci U S A (2010)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1073/pnas.0914658107"}], "href": "https://doi.org/10.1073/pnas.0914658107"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20133602"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20133602"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Kristin M Ates, Tong Wang, Trevor Moreland, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Deficiency in the endocytic adaptor proteins PHETA1/2 impairs renal and craniofacial development."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Dis Model Mech (2020)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1242/dmm.041913"}], "href": "https://doi.org/10.1242/dmm.041913"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "32152089"}], "href": "https://pubmed.ncbi.nlm.nih.gov/32152089"}]}]}]}