The key difference between myristoylation and palmitoylation is that myristoylation is an irreversible process, whereas palmitoylation is a reversible process.
Myristoylation is a type of lipid modification reaction in which a myristoyl group is covalently added through an amide bond to the alpha-amino group of an N-terminal glycine residue. Palmitoylation is a type of lipid modification reaction in which the covalent bonding of fatty acids to cysteine occurs.
CONTENTS
1. Overview and Key Difference
2. What is Myristoylation
3. What is Palmitoylation
4. Myristoylation vs Palmitoylation in Tabular Form
5. Summary – Myristoylation vs Palmitoylation
What is Myristoylation?
Myristoylation is a type of lipid modification reaction in which a myristoyl group is covalently added through an amide bond to the alpha-amino group of an N-terminal glycine residue. The myristoyl group is derived from the myristic acid. Myristic acid is a saturated fatty acid having 14 carbon atoms per molecule. Myristoylation is a lipidation, which is the most found type of fatty acylation in many organisms such as animals, plants, fungi, viruses and protozoans. This reaction involves weak protein–protein and protein–lipid interactions, which has an important role in membrane targeting, functions in signal transduction pathways, etc.
Figure 01: Mechanism of Myristoylation
When considering the mechanism of the Myristoylation reaction, it occurs via nucleophilic addition-elimination reaction. This reaction process is important not only in diversifying the functions of a protein but also in adding layers of regulation to the protein. E.g. This process is involved in membrane association and cellular localization of the modified protein.
What is Palmitoylation?
Palmitoylation is a type of lipid modification reaction in which the covalent bonding of fatty acids to cysteine occurs. The major fatty acid that is being added like this is palmitic acid, and the addition may occur not only to cysteine but also to serine and threonine less frequently. Typically, these proteins are membrane proteins.
Figure 02: A Biochemical Process involving Palmitoylation
Usually, palmitoylation enhances the hydrophobicity of proteins and contributes to the membrane association. It also appears to play an important role in the subcellular trafficking of proteins between membrane compartments and in modulating protein-protein interactions. This chemical process is a dynamic process. It is also a post-translational process.
Moreover, palmitoylation mediates the affinity of a protein for lipid rafts and facilitates the clustering of proteins. This clustering can increase the proximity of the two molecules. Apart from that, the clustering can sequester a protein away from a substrate.
What is the Difference Between Myristoylation and Palmitoylation?
Myristoylation and Palmitoylation are lipid-modifying chemical processes. Myristoylation is a type of lipid modification reaction in which a myristoyl group is covalently added to the alpha-amino group of an N-terminal glycine residue through an amide bond, whereas palmitoylation is a type of lipid modification reaction in which fatty acids are covalently bonded to cysteine. The key difference between myristoylation and palmitoylation is that myristoylation is an irreversible process, whereas palmitoylation is a reversible process. Furthermore, myristoylation reaction involves weak protein–protein and protein–lipid interactions which has an important role in membrane targeting, functions in signal transduction pathways, etc. whereas palmitoylation enhances the hydrophobicity of proteins and it contributes to the membrane association.
The following table summarizes the difference between myristoylation and palmitoylation.
Summary – Myristoylation vs Palmitoylation
Myristoylation and palmitoylation are lipid-modifying chemical processes. The key difference between myristoylation and palmitoylation is that myristoylation is an irreversible process, whereas palmitoylation is a reversible process.
Reference:
1. “Myristoylation.” An Overview | ScienceDirect Topics.
Image Courtesy:
1. “Myristoylation mechanism” By Lengkr – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Gephyrinc” By Borislav Dejanovic,Marcus Semtner,Silvia Ebert,Tobias Lamkemeyer,Franziska Neuser,Bernhard Lüscher,Jochen C. Meier,Guenter Schwarz – figure 9 [1] of “Palmitoylation of Gephyrin Controls Receptor Clustering and Plasticity of GABAergic Synapses“ (CC BY-SA 4.0) via Commons Wikimedia
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