ABO is a modulator of Annexin A7 (ANXA7) GTPase, a member of the annexin family of calcium/phospholipid-binding proteins. ABO can directly bind to Annexin A7 and inhibit its phosphorylation. Annexin A7 is involved in several processes especially in the process of membrane fusion and exocytosis. ABO is a GTPase, and both GTP-binding and Protein kinase C (PKC) activity are important in regulating its function to potentiate calcium-dependent membrane fusion. Annexin A7 has several other activities, not fully understood. ABO suppressed oxidized low-density lipoprotein (oxLDL)-induced phosphatidylcholine-specific phospholipase C (PC-PLC) activity, inhibiting apoptosis and promoting autophagy in vascular endothelial cells, indicating th at ANXA7 is an endogenous regulator of phosphatidylcholine-specific phospholipase C (PC-PLC). ABO significantly reduced atherosclerotic plaque area and reduced lipid deposition and pro-inflammatory macrophages in apolipoprotein E-/- mice. ABO should be a valuable tool to study the complex functions of Annexin 7.
