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Fluorescence-Based Measurements of Phosphatidylserine/Phosphatidylinositol 4-Phosphate Exchange Between Membranes
Published on: March 14, 2021
Characteristics of oxysterol binding proteins.
Daoguang Yan1, Vesa M Olkkonen
1Department of Molecular Medicine, National Public Health Institute, Biomedicum, FI-00290 Helsinki, Finland.
International Review of Cytology
|February 16, 2008
Summary
Oxysterol-binding protein homolog (ORP) proteins, found across eukaryotes, are crucial for sterol transport and cellular regulation. Evolving from ancestral sterol transport roles, mammalian ORPs function as key sterol sensors.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- Oxysterol-binding protein (OSBP)-related (ORP) proteins share a conserved ligand-binding domain across eukaryotes.
- These proteins are implicated in diverse cellular functions, but their precise mechanisms remain unclear.
- Sterol ligand binding is a potential unifying theme for ORP function.
Purpose of the Study:
- To elucidate the diverse functions of OSBP-related (ORP) proteins.
- To investigate the evolutionary divergence of ORP functions from sterol transport.
- To propose a working hypothesis for the primary role of mammalian ORPs.
Main Methods:
- Comparative analysis of ORP families across species (yeast to humans).
- Functional studies on Saccharomyces cerevisiae ORPs.
- Functional studies on mammalian ORPs, including investigations into differential splicing.
Main Results:
- S. cerevisiae ORPs are involved in nonvesicular sterol transport, Golgi-to-cell surface transport, and cell polarity.
- Mammalian ORPs exhibit diverse functions, including roles in sterol and sphingomyelin metabolism, sterol transport, lipid metabolism, endosome/lysosome motility, and signaling.
- Evolution suggests ORP functions diverged from ancestral sterol transport to meet complex regulatory needs in multicellular organisms.
Conclusions:
- ORP proteins play fundamental roles in sterol homeostasis and cellular regulation.
- Mammalian ORPs likely function as critical sterol sensors, integrating lipid metabolism with various cellular processes.
- The complexity of mammalian ORPs reflects their specialized roles in multicellular organisms, evolving from simpler ancestral functions.
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