Serum protein electrophoresis (SPEP) is an easy, inexpensive method of separating proteins based on their net charge, size, and shape. The 2 major types of protein present in the serum are albumin and the globulin proteins.

Albumin is the major protein component of serum and represents the largest peak that lies closest to the positive electrode.

Globulins comprise a much smaller fraction of the total serum protein but represent the primary focus of interpretation of serum protein electrophoresis.

Interpretation of elevation, decreased, or visual change in different fractions can be used as a diagnostic aid for a variety of different disease states and protein abnormalities, including monoclonal gammopathies (MG).

What are globulins?

Globulins are a group of proteins in your blood. They are made in your liver by your immune system.

Globulins play an important role in:

- liver function,

- blood clotting,

and fighting infection.

There are four main types of globulins. They are called

- alpha 1,

- alpha 2,

- beta,

- and gamma.

Just as there are different types of globulins, there are different types of globulin tests.

In general, alpha and gamma globulin protein levels increase when there is inflammation in the body.

The beta fraction has two peaks labeled beta1 and beta2. Beta1 is composed mostly of transferrin, and beta2 contains beta-lipoprotein. IgA, IgM, and sometimes IgG, along with complement proteins, also can be identified in the beta fraction.

References: 

- https://www.aafp.org/afp/2005/0101/p105.html