co-translational protein modification

Definition

Target type: biologicalprocess

The process of covalently altering one or more amino acids in a protein after translation has begun but before the protein has been released from the ribosome. [GOC:jsg]

Co-translational protein modification is a crucial biological process that occurs during the translation of mRNA into protein. Unlike post-translational modifications, which happen after translation, co-translational modifications take place concurrently with protein synthesis. This delicate dance ensures that proteins are correctly folded, targeted to their appropriate locations within the cell, and equipped with the necessary functional groups.

One key aspect of co-translational protein modification is the recognition and targeting of proteins to specific cellular compartments. Ribosomes, the protein synthesis factories, associate with the endoplasmic reticulum (ER) membrane, a vast network within eukaryotic cells. This association is crucial for proteins destined for the ER, Golgi apparatus, lysosomes, or secretion outside the cell. As the nascent polypeptide chain emerges from the ribosome, signal sequences, short stretches of amino acids, act as address labels, guiding the ribosome-mRNA complex to the ER membrane.

Another critical facet of co-translational protein modification is protein folding. As the protein is being synthesized, it starts to fold into its three-dimensional structure. This folding process is often aided by chaperone proteins, which prevent misfolding and aggregation. Co-translational folding allows for efficient and accurate protein assembly, ensuring that the protein assumes its correct shape and function.

Beyond folding, co-translational modifications also involve the addition of functional groups. One common example is glycosylation, where sugars are attached to the protein. Glycosylation plays a role in protein stability, folding, and cell-cell recognition. Additionally, certain amino acid residues may be modified with ubiquitin, a small protein that can target proteins for degradation.

In essence, co-translational protein modification is an orchestrated symphony of events, ensuring that proteins are correctly synthesized, folded, modified, and delivered to their appropriate destinations. This intricate process is fundamental to the proper functioning of cells and organisms, highlighting the remarkable efficiency and complexity of cellular machinery.'
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Proteins (1)

Compounds (2)