Globulin is one of the two types of serum proteins, the other being albumin. This generic term encompasses a heterogenous series of families of proteins, with larger molecules and less soluble in pure water than albumin, which migrate less than albumin during serum electrophoresis.

It is sometimes used synonymously with Globular protein. However, albumin is also a globular protein, but not a globulin. All other serum globular proteins are globulins.

Protein electrophoresis is used to categorize globulins into the following four categories:

• Alpha 1 globulins
• Alpha 2 globulins
• Beta globulins
• Gamma globulins (immunoglobulins)