Serum Amyloid A (SAA) Proteins

As normal constituents of blood serum, the Serum Amyloid ASerum Amyloid A (SAA) (SAA) proteinsProteins are small (104 amino acids in humans) and remarkably well-conserved in mammalian evolution. They are synthesized prominently, but not exclusively, in the liver. Fragments of SAASerum Amyloid A (SAA) can associate into insoluble fibrils (called “amyloid”) characteristic of “secondary” amyloid disease in which they can interrupt normal physiology and lead to organ failure. SAASerum Amyloid A (SAA) proteinsProteins comprise a family of molecules, two members of which (SAA1 and SAA2) are (along with C-reactiveProteins proteinC-reactive protein (CRP), CRP) the most prominent members of the acute phase responseAcute Phase Response (APR) (APR) during which their serum levels rise dramatically after trauma, infection and other stimuli. Biologic functionFunction (s) of SAASerum Amyloid A (SAA) are unresolved but features are consistent with a prominent role in primordial host defense (including the APRAcute Phase Response (APR) ). SAASerum Amyloid A (SAA) proteinsProteins are lipophilic and contribute to high densityLipoproteins lipoproteinsHigh-Density Lipoproteins (HDL) (HDL) and cholesterol transport. SAASerum Amyloid A (SAA) proteinsProteins interact with specific receptors and have been implicated in tissue remodeling through metalloproteinases, local tissue changes in atherosclerosisAtherosclerosis, cancer metastasisMetastasis, lung inflammationInflammation, maternal–fetal health and intestinal physiology. Molecular details of some of these are emerging.