Difference Between Fibronectin and Vitronectin

The key difference between fibronectin and vitronectin is that fibronectin is a high molecular weight cell-adhesive glycoprotein normally found in plasma and extracellular matrix, while vitronectin is a low molecular weight cell-adhesive glycoprotein normally found in serum, extracellular matrix, and bone.

Fibronectin and vitronectin are two cell adhesive glycoproteins. Cell adhesive glycoproteins are also known as multifunctional adhesive glycoproteins. They are a subset of proteins generally located in the plasma and extracellular matrix. Fundamentally, most adhesive glycoproteins bind cells through cell surface receptor integrin. They also can bind to other receptors such as dystroglycans and syndecans. They interact with these receptors and also with other extracellular matrix proteins to form an intensive matrix network. Cell adhesion is a critical component in maintaining tissue structure and function.

CONTENTS

1. Overview and Key Difference
2. What is Fibronectin 
3. What is Vitronectin
4. Similarities – Fibronectin and Vitronectin
5. Fibronectin vs Vitronectin in Tabular Form
6. Summary –Fibronectin vs Vitronectin

What is Fibronectin?

Fibronectin is a high molecular weight cell adhesion glycoprotein found in plasma and extracellular matrix. It is a high molecular weight (500 kDa) glycoprotein. Fibronectin usually binds to a cell surface receptor called “integrin.” Fibronectin also binds to other extracellular matrix proteins such as collagen, fibrin, heparin sulfate, proteoglycans (syndecans), etc. This protein exists as a dimer. It consists of two nearly identical monomers linked by a pair of disulfide bonds. FN1 gene codes for fibronectin protein.

Generally, the fibronectin protein is produced by a single gene. But alternative splicing of pre mRNA of this protein creates several isoforms of this protein.

Types and Functions of Fibronectins

Two types of fibronectins are present in vertebrates as soluble plasma fibronectin and insoluble cellular fibronectin. Soluble plasma fibronectin is a component of blood plasma, and it is produced in the liver by hepatocytes. Insoluble cellular fibronectin is a component of the extracellular matrix. It is secreted by various cells such as fibroblasts. Furthermore, this protein plays a key role in cell adhesion, growth, migration, and differentiation. It is also extremely important for wound healing and embryonic development. The altered expression, degradation, and organization of this protein have been associated with various diseases such as cancer, arthritis, and fibrosis.

What is Vitronectin?

Vitronectin is a low molecular weight cell-adhesive glycoprotein found in serum, extracellular matrix, and bone. Its molecular weight is around 54 kDa. Vitronectin belongs to the hemopexin family. In humans, the gene coding this protein is the VTN gene. Vitronectin usually binds to cell surface receptors known as integrin alpha-Vbeta-3 and thus promotes cell adhesion and spreading.

Further, it inhibits the membrane damaging effect of the terminal cytolytic complement pathway. It also binds to several serine protease inhibitors like serpins. This protein is a secreted protein. It exists as either a single-chain form or two chains form. If it exists as two chains form, these chains are held together by a disulfide bond. Moreover, this protein has been speculated to be involved in tumor malignancy.

What are the Similarities Between Fibronectin and Vitronectin?

• Fibronectin and vitronectin are cell adhesive proteins.
• They are glycoproteins.
• They both bind to a cell surface receptor called “inetgrin.”
• They are present in the extracellular matrix.
• The altered expression of both these proteins causes cancer.

What is the Difference Between Fibronectin and Vitronectin?

Fibronectin is a high molecular weight cell-adhesive glycoprotein in plasma and extracellular matrix. On the other hand, vitronectin is a low molecular weight cell-adhesive glycoprotein in serum, extracellular matrix, and bone. So, this is the key difference between fibronectin and vitronectin. Furthermore, the altered expression, degradation, and organization of fibronectin have been associated with various diseases such as cancer, arthritis, and fibrosis, while altered expression of vitronectin has been involved in diseases such as tumor malignancy. Thus, this is another significant difference between fibronectin and vitronectin.

The below infographic tabulates the differences between fibronectin and vitronectin.

Summary – Fibronectin vs Vitronectin

Cell adhesion is the process by which cells interact and attach to each other. Cell adhesive glycoproteins bind cells through cell surface integrin receptors in conjunction with other cell surface receptors. Fibronectin and vitronectin are two cell adhesive glycoproteins. Fibronectin is a high molecular weight cell-adhesive glycoprotein that is normally found in plasma and extracellular matrix. On the other hand, vitronectin is a low molecular weight cell-adhesive glycoprotein that is normally found in serum, extracellular matrix, and bone. Thus, this is the summary of the difference between fibronectin and vitronectin.

Reference:

1. “Fibronectin.” An Overview | ScienceDirect Topics.
2. “Vitronectin.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “1fbr human fibronectin FourthAndFifthFibronectinTypeIModulePai04” By Nevit Dilmen – Self created from PDB entry with Cn3D Data Source (CC BY-SA 3.0) via Commons Wikimedia
2. “Serpin latent state” By Thomas Shafee – Own work (CC BY 4.0) via Commons Wikimedia