Sack George H
Departments of Biological Chemistry and Medicine, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Physiology 615, Baltimore, MD, 21205, USA.
Subcell Biochem. 2020;94:421-436. doi: 10.1007/978-3-030-41769-7_17.
As normal constituents of blood serum, the Serum Amyloid A (SAA) proteins 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 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. SAA proteins comprise a family of molecules, two members of which (SAA1 and SAA2) are (along with C-reactive protein, CRP) the most prominent members of the acute phase response (APR) during which their serum levels rise dramatically after trauma, infection and other stimuli. Biologic function (s) of SAA are unresolved but features are consistent with a prominent role in primordial host defense (including the APR ). SAA proteins are lipophilic and contribute to high density lipoproteins (HDL) and cholesterol transport. SAA proteins interact with specific receptors and have been implicated in tissue remodeling through metalloproteinases, local tissue changes in atherosclerosis, cancer metastasis, lung inflammation, maternal-fetal health and intestinal physiology. Molecular details of some of these are emerging.
血清淀粉样蛋白A（SAA）蛋白作为血清的正常成分，分子量较小（人类为104个氨基酸），在哺乳动物进化过程中高度保守。它们主要在肝脏中合成，但并非仅在肝脏合成。SAA片段可聚合成不溶性纤维（称为“淀粉样蛋白”），这是“继发性”淀粉样变性疾病的特征，在该疾病中它们可干扰正常生理功能并导致器官衰竭。SAA蛋白构成一个分子家族，其中两个成员（SAA1和SAA2）（与C反应蛋白，CRP一起）是急性期反应（APR）中最突出的成员，在创伤、感染和其他刺激后，它们的血清水平会急剧上升。SAA的生物学功能尚未明确，但有迹象表明其在原始宿主防御（包括急性期反应）中起重要作用。SAA蛋白具有亲脂性，有助于高密度脂蛋白（HDL）和胆固醇转运。SAA蛋白与特定受体相互作用，并通过金属蛋白酶参与组织重塑、动脉粥样硬化的局部组织变化、癌症转移、肺部炎症、母婴健康和肠道生理功能。其中一些的分子细节正在逐渐显现。
