Detailed Explanation
Chemical change to a peptide or protein after it has been synthesized by the ribosome. PTMs vastly expand the functional diversity of the proteome beyond what the genetic code alone encodes.
Major PTMs include phosphorylation (kinases add phosphate to Ser/Thr/Tyr — the most common PTM), glycosylation (addition of sugar chains — affects folding, stability, and immune recognition), acetylation (acetyl groups on N-terminus or Lys — regulates gene expression via histone modification), methylation (methyl groups on Lys/Arg — epigenetic regulation), ubiquitination (ubiquitin tagging for proteasomal degradation), and proteolytic cleavage (converting inactive propeptides to active forms, e.g., proinsulin → insulin). Over 400 distinct PTM types have been identified.
Key Facts
- Chemical change to a peptide or protein after it has been synthesized by the ribosome.
- PTMs vastly expand the functional diversity of the proteome beyond what the genetic code alone encodes.
- Major PTMs include phosphorylation (kinases add phosphate to Ser/Thr/Tyr — the most common PTM), glycosylation (addition of sugar chains — affects folding, stability, and immune recognition), acetylation (acetyl groups on N-terminus or Lys — regulates gene expression via histone modification), methylation (methyl groups on Lys/Arg — epigenetic regulation), ubiquitination (ubiquitin tagging for proteasomal degradation), and proteolytic cleavage (converting inactive propeptides to active forms, e.g., proinsulin → insulin).
- Over 400 distinct PTM types have been identified.
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