Inositol phosphates are water-soluble intracellular signaling molecules found in eukaryotes from yeasts to mammals, which are synthesized by a complex network of enzymes including inositol phosphate kinases. Among these, inositol polyphosphate multikinase (IPMK) is a promiscuous enzyme with broad substrate specificity, which phosphorylates multiple inositol phosphates, as well as phosphatidylinositol 4,5-bisphosphate. In addition to its catalytic actions, IPMK is known to non-catalytically control major signaling events via direct protein-protein interactions. In this review, we describe the general characteristics of IPMK, highlight its pleiotropic roles in various physiological and pathological conditions, and discuss future challenges in the field of IPMK signaling pathways.
Gavin Herbert Eye Institute - Center for Translational Vision Research, Department of Ophthalmology, University of California, Irvine, Irvine, California 92697, United States.
Arrestins halt signal transduction by binding to the phosphorylated C-termini of activated G protein-coupled receptors. Arrestin-1, the first subtype discovered, binds to rhodopsin in rod cells. Mutations in , the gene encoding Arrestin-1, are linked to Oguchi disease, characterized by delayed dark adaptation.
Inositol hexakisphosphate (InsP ), also known as phytic acid, is a potent chelator of bivalent cations. Intracellular InsP molecules are associated with magnesium. Calcium is the prevalent bivalent cation outside the cell and its association with InsP could lead to the formation of insoluble complexes.
Phosphate (Pi) homeostasis at the cellular level is crucial, requiring coordinated Pi uptake, storage, and export. However, the regulatory mechanisms, particularly those governing Pi export, remain elusive, despite their relevance to human diseases like primary familial brain calcification. While Xpr1, conserved across eukaryotes, is the only known Pi exporter, the existence of additional Pi exporting factors is evident; however, these factors have been poorly characterized.
The gene inositol polyphosphate-5-phosphatase D (INPP5D), which encodes the lipid phosphatase SH2-containing inositol polyphosphate 5-phosphatase 1 (SHIP1), is associated with the risk of Alzheimer's disease (AD). How it influences microglial function and brain physiology is unclear. Here, we showed that SHIP1 was enriched in early stages of healthy brain development.
Quercetin, a bioflavonoid abundant in plants, boasts antioxidant properties and plays a crucial role in various biological systems. The diffraction data of a quercetin dihydrate crystal have been measured at 20 (2) K to ultrahigh resolution (0.30 Å) using a synchrotron X-ray source.
