Oxysterol-binding protein-related protein 4 (ORP4)

Oxysterol-binding protein-related protein 4 is a cytosolic lipid transfer protein with a conserved oxysterol-binding domain and pleckstrin homology motif, controlling the movement of sterols (cholesterol, 25-hydroxycholesterol) and phospholipids (phosphatidylinositol-4-phosphate) between cell membranes[1][3][7][8]. ORP4 is expressed in human brain, heart, muscle, and kidney, and exists as several isoforms with distinct cellular localization and functions[1][3][8]. ORP4 is uniquely required for the proliferation and survival of rapidly dividing and transformed cells, supporting intracellular calcium homeostasis and activating gene clusters that sustain cell growth[4][5]. It interacts with vimentin intermediate filaments, regulating cytoskeletal organization and cholesterol transport[1][3][4][8]. Small-molecule inhibition of ORP4 impairs cancer cell viability, making it a potential therapeutic target in oncology and antiviral research[13][15].

Other names

OSBP-related protein 4OSBP2HLMORP4L (long isoform)ORP4M (medium isoform)ORP4S (short isoform)

Inhibition of ORP4 impairs cancer cell proliferation and survival by modulating lipid homeostasis, calcium signaling, and apoptosis