Globulin

To be distinguished from globin which is the name for the fold found in haemoglobin or immunoglobulin which is the name for the antibody fold.

Crystallins, in contrast are found in the eye, but are yet another architecture of protein, technically a greek key fold.

Refers to a kind of protein that is carried in the liquid part of the blood (plasma). There are three classes of globulin: alpha, beta, and gamma. Each can be subdivided further; for example, there is an alpha I and an alpha II globulin. Each of the globulin proteins has an important function in the body.

Alpha and beta globulins combine loosely with other important body chemicals to carry them around in the blood. Alpha I globulin contains a fraction that binds bilirubin and another one that carries steroids and lipids. Alpha II globulin combines with free hemoglobin in the plasma. Beta globulins include some that are responsible for transporting lipids and others that bind copper and iron for transport. Prothrombin, one of the blood-clotting factors, is a beta globulin. The gamma globulins are extremely important in the body’s immune system: They are known alternatively as immunoglobulins and are subdivided into classes (IgA, IgE, igM, etc.) according to their function.

The overall pattern of alpha, beta, and gamma globulins may be measured to assess the progress of many different types of disease and treatment, since they quite commonly are affected. The specific immunoglobulins are also useful diagnostic indicators.

Glob"u*lin (?), n. [From Globule: cf. F. globuline.] Phisiol. Chem.

An albuminous body, insoluble in water, but soluble in dilute solutions of salt. It is present in the red blood corpuscles united with haematin to form haemoglobin. It is also found in the crystalline lens of the eye, and in blood serum, and is sometimes called crystallin. In the plural the word is applied to a group of proteid substances such as vitellin, myosin, fibrinogen, etc., all insoluble in water, but soluble in dilute salt solutions.

 

© Webster 1913.