Proteins produced and secreted by the liver

Major plasma proteins

• Human serum albumin, osmolyte and carrier protein
• α-fetoprotein, the fetal counterpart of serum albumin
• Soluble plasma fibronectin, forming a blood clot that stops bleeding
• C-reactive protein, opsonin on microbes, acute phase protein
• Various other globulins

  Factors in hemostasis and fibrinolysis

• Stimulators of coagulation:
• *All factors in the coagulation cascade.
• *While the endothelium does produce some factor VIII, the majority of factor VIII is produced in the liver.
• Inhibitors of coagulation: Inactivate an enormous variety of proteinases
• *α2-macroglobulin
• *α1-antitrypsin
• *Antithrombin III
• *Protein S
• *Protein C
• Fibrinolysis: Breakdown of fibrin clots
• *Plasminogen
• Inhibitors of fibrinolysis
• *α2-antiplasmin
• Complement components C1-9, complement component 3

  Carrier proteins

• Albumin, carries thyroid hormones and other hormones, particularly fat soluble ones, fatty acids to the liver, unconjugated bilirubin, many drugs and Ca²⁺
• Ceruloplasmin, carries copper
• Transcortin, carries cortisol, aldosterone and progesterone
• Haptoglobin, carries free hemoglobin released from erythrocytes
• Hemopexin, carries free heme released from hemoglobin
• IGF binding protein, carries insulin-like growth factor 1
• Major urinary proteins, carries pheromones in rodents
• Retinol binding protein, carries retinol
• Sex hormone-binding globulin, carries sex hormones, specifically testosterone and estradiol
• Thyroxine-binding globulin, carries the thyroid hormones thyroxine and 3,5,3’-triiodothyronine
• Transthyretin, carries the thyroid hormone thyroxine
• Transferrin, carries iron ions in the ferric form
• Vitamin D-binding protein, carries vitamin D

  Hormones

• FGF21, a protein hormone that induces mitochondrial oxidation of fatty acids, hepatic gluconeogenesis, and ketogenesis in response to fasting.
• Hepcidin, a peptide hormone that regulates iron homeostasis.
• Insulin-like growth factor 1, a polypeptide protein hormone which plays an important role in childhood growth and continues to have anabolic effects in adults
• Thrombopoietin, a glycoprotein hormone that regulates the production of platelets by the bone marrow

  Prohormones

• Angiotensinogen, when converted to angiotensin causes vasoconstriction and release of aldosterone, in effect increasing blood pressure

  Apolipoproteins

• Almost all apolipoprotein, except apo B48