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Covalently Linked Protein Regulators

Covalently Linked Protein Regulators

Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.

Phosphorylation

Phosphorylation

The addition or removal of phosphate groups from proteins is the most common chemical modification that regulates cellular processes. These modifications can affect the structure, activity, stability, and localization of proteins within cells as well as their interactions with other proteins.
During phosphorylation, protein kinases transfer the terminal phosphate group of ATP to specific amino acid side chains of substrate proteins. Serine, threonine, and tyrosine are the most commonly...

Protein Kinases and Phosphatases

Protein Kinases and Phosphatases

Proteins undergo chemical modifications that trigger changes in the charge, structure, and conformation of the proteins. Phosphorylation, acetylation, glycosylation, nitrosylation, ubiquitination, lipidation, methylation, and proteolysis are various protein modifications that regulate protein activity. Such modifications are usually enzyme-driven.
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...

Protein Modifications in the RER

Protein Modifications in the RER

Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.

Bacterial Protein Maturation

Bacterial Protein Maturation

Bacterial protein maturation is a tightly regulated process that ensures newly synthesized polypeptides achieve correct functional conformations. This maturation involves a series of modifications, folding events, and quality control steps, often assisted by specialized chaperone proteins.N-Terminal ModificationsThe maturation of bacterial polypeptides begins cotranslationally as the polypeptide exits the ribosome. The first amino acid, N-formylmethionine (fMet), is typically modified at the...

Regulation of Expression at Multiple Steps

Regulation of Expression at Multiple Steps

The gene expression in cells is regulated at different stages: (i) transcription, (ii) RNA processing, (iii) RNA localization, and (iv) translation. Transcriptional regulation is mediated by regulatory proteins such as transcription factors, activators, or repressors—these control gene expression by initiating or inhibiting the transcription of genes. Once a precursor or pre-mRNA is produced, it undergoes post-transcriptional modification, including 5' capping, splicing, and the addition of a...

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Related Experiment Video

Updated: May 20, 2026

Simultaneous Affinity Enrichment of Two Post-Translational Modifications for Quantification and Site Localization

Simultaneous Affinity Enrichment of Two Post-Translational Modifications for Quantification and Site Localization

Published on: February 27, 2020

Systematic functional prioritization of protein posttranslational modifications.

Pedro Beltrao¹, Véronique Albanèse, Lillian R Kenner

¹Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94107, USA. pedro.beltrao@ucsf.edu

|July 24, 2012

Summary

Scientists analyzed over 200,000 posttranslational modification (PTM) sites across species. They developed methods to identify functionally important PTMs, revealing that only a fraction of sites significantly impact biological roles.

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A Fast and Quantitative Method for Post-translational Modification and Variant Enabled Mapping of Peptides to Genomes

A Fast and Quantitative Method for Post-translational Modification and Variant Enabled Mapping of Peptides to Genomes

Published on: May 22, 2018

Related Experiment Videos

Last Updated: May 20, 2026

Simultaneous Affinity Enrichment of Two Post-Translational Modifications for Quantification and Site Localization

Simultaneous Affinity Enrichment of Two Post-Translational Modifications for Quantification and Site Localization

Published on: February 27, 2020

A Fast and Quantitative Method for Post-translational Modification and Variant Enabled Mapping of Peptides to Genomes

A Fast and Quantitative Method for Post-translational Modification and Variant Enabled Mapping of Peptides to Genomes

Published on: May 22, 2018

Area of Science:

Molecular Biology
Proteomics
Bioinformatics

Background:

Posttranslational modifications (PTMs) regulate protein function, with mass spectrometry rapidly increasing PTM identification.
The functional significance of most identified PTMs remains largely unknown.
Understanding PTMs is crucial for deciphering complex cellular processes.

Purpose of the Study:

To develop methods for prioritizing the functional relevance of PTMs.
To identify PTMs involved in cross-regulation, domain activity, and protein-protein interactions.
To analyze the evolutionary conservation and biological significance of PTMs.

Main Methods:

Compiled a dataset of ~200,000 phosphorylation, acetylation, and ubiquitination sites from 11 eukaryotic species.
Developed predictive methods to assess PTM functional relevance.
Analyzed PTM conservation within domain families and experimentally validated findings on the HSP70 domain family.

Main Results:

Identified conserved PTMs within domain families as regulatory "hot spots" overlapping functionally important regions.
Experimental validation confirmed the importance of these conserved PTMs in the HSP70 domain family.
Analysis suggests that only a fraction of PTM sites possess significant biological roles, with potential for neutral drift in regulatory interactions.

Conclusions:

Developed a framework to prioritize functionally relevant PTMs.
PTM conservation is a strong indicator of functional importance.
The study highlights the selective pressure on regulatory PTMs and suggests a limited subset drives significant biological outcomes.