Key Difference – Globin vs Globulin
Globin and globulins are major proteins of an organism. They are specialized for important functions in the blood stream. Globin proteins are specialized for oxygen binding and transporting oxygen from respiratory organs to other tissues. They are bound to heme groups. Globulins are a major type of blood proteins found in serum. They are responsible for several functions of the blood. The key difference between globin and globulin is that globins are heme-containing globular proteins while globulins are simple globular proteins.
CONTENTS
1. Overview and Key Difference
2. What is Globin
3. What is Globulin
4. Side by Side Comparison – Globin vs Globulin
5. Summary
What is Globin?
Globin is a superfamily of proteins found in the blood. They are popular as heme-containing globular proteins. There are two popular members of globin family namely hemoglobin and myoglobin. The major function of the globin protein is the transportation of oxygen from respiratory organs to other organs via red blood cells. Globin proteins are composed of several polypeptides. They contain multi-subunit globular proteins.
In vertibrates, eight different globin proteins can be found. They are cytoglobin, androglobin, globin E, globin X, globin Y, myoglobin, haemoglobin, and neuroglobin. In bacteria, algae and cyanobacteria, globin proteins exist in different types.
Figure 01: Myoglobin Protein
What is Globulin?
Globulin is a simple globular protein found in the blood plasma. It is a major blood protein and accounts for half of the blood proteins. Globulin protein is soluble in salt and insoluble in water. Globulin proteins are involved in several functions in the blood such as transporting metabolites and metals and functioning as immunoglobulins. Globulin concentration in human blood is about 2.6 – 4.6 g/dL. Globulins are in various sizes ranging from 93 kDa (lightest alpha globulin) to 1193 kDa (heaviest gamma globulin). Most of the globulin proteins are synthesized in the liver and immunoglobulins are produced by plasma cells.
Some globulins are immunologically active; they are referred as immunoglobulins or popular antibodies. Other globulin proteins act as carrier proteins, enzymes and complements in the blood. There are four major groups of globulin proteins. They are Alpha 1 globulins, Alpha 2 globulins, Beta globulins and Gamma globulins. Immunoglobulins belong to Gamma globulins and are a critical part of the immune system which protects the body from the pathogens.
Figure 02: Immunoglobulin Structure
What is the difference between Globin and Globulin?
Globin vs Globulin |
|
| Globin is a larger protein family. | Globulin is a protein found in the blood plasma. |
| Main Function | |
| Globin proteins are involved mainly in oxygen transportation in the organisms. | Globulin proteins are involved with several functions in the blood including immune responses, enzymatic actions, transportation of metals, etc. |
| Members | |
| Two prominent members of globin protein are hemoglobin and myoglobin. | Immunoglobulins are one of the major types of globulins in the blood plasma. |
| Structure | |
| Globin protein has several polypeptides folded together. | Globulin protein is a simple protein. |
Summary – Globin vs Globulin
Globin proteins are involved with oxygen transportation in the blood. They are popular as heme-containing proteins. Globulins are a group of blood proteins found in blood plasma. They function as enzymes, carrier proteins, complements and antibodies in the blood. Thus, the main difference between globin and globulin is their function.
References
1. Miller, L. L., F. S. Robscheit-Robbins, and G. H. Whipple. “HEMOGLOBIN AND PLASMA PROTEIN : THEIR RELATION TO INTERNAL BODY PROTEIN METABOLISM.” The Journal of Experimental Medicine. The Rockefeller University Press, 01 May 1945. Web. 10 Apr. 2017
2. Götting, Miriam, and Mikko Nikinmaa. “More than hemoglobin – the unexpected diversity of globins in vertebrate red blood cells.” Physiological Reports. BlackWell Publishing Ltd, Feb. 2015. Web. 11 Apr. 2017
Image Courtesy:
1. “Myoglobin-1mba”By Opabinia regalis – Self created from PDB entry IMBA using the freely available visualization and analysis package VMD (CC BY-SA 3.0) via Commons Wikimedia
2. Antibody IgG2″ 由英语维基百科的TimVickers – 從en.wikipedia轉移到共享資源 (Public Domain) via Commons Wikimedia