Fehérjemetiláció

Fehérjemetiláció is a post-translational modification where a methyl group is added to a protein. This process primarily occurs on the nitrogen atoms of lysine or arginine residues, though it can also happen on cysteine or histidine residues. The methyl group is typically transferred from S-adenosylmethionine (SAM), a universal methyl donor in biological systems. Enzymes called methyltransferases catalyze this reaction.

The addition of methyl groups can significantly alter the properties and function of a protein. Methylation can affect protein-protein interactions, protein-DNA interactions, protein localization within the cell, and enzyme activity. For example, methylation of histones, proteins that package DNA, plays a crucial role in regulating gene expression. Lysine methylation on histones can either activate or repress transcription depending on the specific site and the presence of other modifications. Similarly, methylation of other proteins can influence signaling pathways and cellular processes.

The reversibility of methylation is also important. Enzymes known as demethylases can remove methyl groups, allowing for dynamic regulation of protein function. This on-and-off switching is critical for cellular responses to stimuli and for maintaining cellular homeostasis. Aberrant protein methylation has been implicated in various diseases, including cancer and neurological disorders, highlighting its importance in health and disease. Research into fehérjemetiláció continues to uncover new roles and regulatory mechanisms of this fundamental biological process.