The globulins are a family of globular proteins that have higher molecular weights than albumins and are insoluble in pure water but dissolve in dilute salt solutions. Some globulins are produced in the liver, while others are made by the immune system. Globulins, albumins, and fibrinogen are the major blood proteins. The normal concentration of globulins in human blood is about 2.6-3.5 g/dL.
The term "globulin" is sometimes used synonymously with "globular protein". However, albumins are also globular proteins, but are not globulins. All other serum globular proteins are globulins.