angiopoietin-related protein 4; angiopoietin-like protein 4; hepatic fibrinogen/angiopoietin-related protein; HFARP (ANGPTL4, ARP4, HFARP, PGAR, PP1158, PSEC0166, UNQ171/PRO197)
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Function
- may act as a regulator of angiogenesis & modulate tumorgenesis
- inhibits proliferation, migration, & tubule formation of endothelial cells & reduces vascular leakage
- may exert a protective function on endothelial cells through an endocrine action
- role in regulating glucose homeostasis, lipid metabolism, & insulin sensitivity
- in response to hypoxia, the unprocessed form of the protein accumulates in the subendothelial extracellular matrix (ECM).
- the matrix-associated & immobilized unprocessed form limits the formation of actin stress fibers & focal contacts in the adhering endothelial cells & inhibits their adhesion
- also decreases motility of endothelial cells & inhibits the sprouting & tube formation (putative)
- the homooligomer undergoes proteolytic processing to release its carboxyl fibrinogen-like domain, which circulates as a monomer
- the homooligomer unprocessed form is able to interact with the extracellular matrix (putative)
Structure
- N-glycosylated
- homooligomer
- contains 1 fibrinogen C-terminal domain
Compartment
- secreted, secreted, extracellular space, extracellular matrix (putative)
- the unprocessed form interacts with the extracellular matrix
- this may constitute a dynamic reservoir, a regulatory mechanism of the bioavailability of ANGPTL4 (putative)
Expression
- hypoxia-induced expression in endothelial cells
- high expression in the placenta, heart, liver, muscle, pancreas & lung
- low expression in brain & kidney