What is the Difference Between Glycoprotein and Mucoprotein

The main difference between glycoprotein and mucoprotein is that glycoproteins have a carbohydrate quantity of less than 4%, whereas mucoproteins have a carbohydrate quantity higher than 4%.

Glycoproteins and mucoproteins are two types of proteins with additional compounds attached to them. These are present in different parts of the body and perform specific functions.

Key Areas Covered

1. What is Glycoprotein 
     – Definition, Features
2. What is Mucoprotein
     – Definition, Features
3. Difference Between Glycoprotein and Mucoprotein
     – Comparison of Key Differences

Key Terms

Glycoprotein, MucoproteinDifference Between Glycoprotein and Mucoprotein - Comparison Summary

What is Glycoprotein

Glycoprotein is a type of protein in which carbohydrate molecules are attached to the peptidoglycan chain. In other words, they are the protein molecules in which the oligosaccharides are covalently attached to amino acid side chains. We call this binding process glycosylation, and these oligosaccharides are glycans. They are saccharine polymers that can attach amino acids or lipids, and form glycoproteins and glycolipids, respectively. Moreover, there are different forms of glycosylation depending on the attachment of specific glycans to proteins and lipids. Some of the common carbohydrate constituent attachments are N-acetylglucosamine, β-D-mannose, β-D-glucose, and β-D-galactose. Additionally, glycoproteins occur naturally. Some examples of such naturally occurring glycoproteins are antibodies, immunoglobins, collagen, transferrin, and histocompatibility antigens. Furthermore, the hydrophilicity of glycoproteins is higher than that of the normal proteins due to the presence of -OH groups in sugars, meaning the glycoproteins have a higher affinity to water than other proteins.

Compare Glycoprotein and Mucoprotein - What's the difference?

The carbohydrate part attaches to the protein molecule through the OH group of serine or threonine or through the amide NH2 of asparagine. This results in two types of glycoproteins depending on the location of the carbohydrate attachment to an amino acid. N-linked glycoproteins have their carbohydrate attached to the nitrogen of asparagine’s amino group via N-glycosylation, and the sugar is provided by the endoplasmic reticulum. This sugar then undergoes procession in the Golgi complex. O-glycosylation occurs when the carbohydrate attaches to the hydroxyl group of threonine or serine’s R group amino acids.

Functions of Glycoproteins

There are many functions of glycoproteins. Glycoproteins are present in cell membranes. They help to cope with aquatic environments easily due to the presence of hydrophilic heads. These glycoproteins also play a role in cell-to-cell recognition and chemical bonding. Glycoproteins present in the grey matter of the brain involve synaptosomes and axons. Resistance of plants to gravity is due to the glycoproteins present in the cells. Furthermore, the process of coagulation requires glycoproteins like thrombin, prothrombin, and fibrinogen.

What is Mucoprotein

Mucoprotiens are a type of conjugated protein. They have a carbohydrate quantity higher than 4% by weight. They are a complex type of protein and contain polysaccharides attached to them. A few examples of mucoproteins are mucus, enzymes, antibiotics, epithelial cells, and some proteins. It is a type of glycoprotein that mainly has mucopolysaccharides. Mucoprotiens are present in the globulin fraction of blood plasma. It is also present in the airways, reproductive organs, gastrointestinal tract, and the synovial fluid of the knees. Furthermore, the production of mucoproteins occurs in the cecum of the gastrointestinal tract. They also provide the function of lubrication.

Moreover, the body of a person with gallbladder cancer has high amounts of mucoproteins. Additionally, a brain injury that lasts long can reduce the content of mucoproteins in the body.

Difference Between Glycoprotein and Mucoprotein

Definition

Glycoprotein is a type of protein in which carbohydrate molecules are attached to the peptidoglycan chain, while mucoprotein is a type of conjugated protein that contains polysaccharides attached to them.

Carbohydrate Content

Glycoproteins have less than 4% carbohydrates, whereas mucoproteins have higher than 4% carbohydrates.

Attachment of Carbohydrates

Moreover, in glycoproteins, carbohydrates are attached in the form of complex branched structures. However, in mucoproteins, the carbohydrates are covalently attached in the form of long chains of repeating disaccharide units called glycosaminoglycans.

Conclusion

Glycoproteins and mucoproteins are two types of proteins. These are present in various parts of the body and perform specific functions. The main difference between glycoprotein and mucoprotein is that glycoproteins have a carbohydrate quantity of less than 4%, whereas mucoproteins have a carbohydrate quantity higher than 4%.

Reference:

1. Osman, Shabir. “What is a Glycoprotein?” New Medical – Life Sciences.
2. “Mucoprotein.” Oxford Reference.

Image Courtesy:

1. “0303 Lipid Bilayer With Various Components” By OpenStax (CC BY 4.0) via Commons Wikimedia

About the Author: Hasini A

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