This document discusses post-translational modifications (PTMs), which are covalent modifications of proteins after translation. PTMs play a crucial role in generating protein diversity and regulating protein function. Some key PTMs discussed include phosphorylation, glycosylation, methylation, acetylation, and lipidation. PTMs occur through the addition of chemical groups like phosphate, carbohydrates, methyl, and lipids to amino acid side chains. They are important for processes like cell signaling, apoptosis, and controlling protein localization and activity. Mass spectrometry and gel electrophoresis are techniques used to detect PTMs.

1. POST TRANSLATION
MODIFICATION(COVALENT
MODIFICATION)
-GENE EXPRESSION IN EUKARIYOTES
NAME: DHRUVI SUVAGIYA
CLASS:MSC SEM 3

2. A LITTLE BACKGROUND –
GENE EXPRESSION
IN EUKARYOTES

3. WHAT IS POST TRANSLATION
MODIFICATION??
• Post-translational modification (PTM) refers to the covalent and
generally enzymatic modification of proteins
• Proteins are synthesized by ribosomes translating mRNA into
polypeptide chains, which may then undergo PTM to form the
mature protein product.
• Post-translational modifications can occur on the amino acid side
chains or at the protein's C- or N- terminal.
• They can extend the 20 standard amino acids by modifying an
existing functional group or introducing a new one such
as phosphate, methane, lipid residues,etc.for regulating the activity
of enzymes and is the most common post-translational.

4. WHY PTMs ARE NECESSARY??
• Play a crucial role in generating the heterogeneity in proteins.
• Help in utilizing identical proteins for different cellular
functions in different cell types.
• Regulation of particular protein sequence behaviour in most of
the eukaryotic organisms.
• Play an important part in modifying the end product of
expression.
• Contribute towards biological processes and diseased
conditions.
• Translation of proteins across biological membranes.

5. TYPES OF PTMs??
PTMs TYPES
TRIMMING
COVALENT
MODIFICATION
UBIQUITINATION

6. COVALENT BOND MODIFICATION
• The proteins synthesized in translation are subjected to many
covalent changes.
• By these modifications in the amino acids the proteins may be
converted to active form or inactive form.
• These including,..
phosphorylation,
glcosylation,
methylation,
alkaylation,
lipoylation,
sulfation,
Carboxylation,
acetylation.

8. Phosphorylation
• Addition of phosphate group to protein.
• Principally on serine, threonine or tyrosine residues.
• Also known as phospho regulation
• Play crucial role in cell growth, cell cycle, apoptosis and
signal transduction.

9. Glycosylation
• The covalent attachment of oligosaccharides
• Addition of glycol group to protein.
• Principally on aspargine,hydroxylysine,serine or threonine.
• Play role in protein folding, conformation, distribution,
stability and protein activity.

10. Methylation
• Addition of methyl group to protein
• Usually at lysine or arginine residues,
• Binds on nitrogen and oxygen of proteins
• Play role in histone methylation –important regulator of
chromatin structure.

11. N-Acylation
• Addition of acetyl group at nitrogen group.
• Histone are acetylated on lysis residues in the n terminal tail as
a part of gene regulation.
• Play role in regulation of transcription factors, effector
proteins, molecular chaperon and cytoskeletoetal proteins.
• Methionine amino peptidase is an enzyme responsible for n
terminal acetylation.

12. Disulphide bonding
• Covalent bond formed between two cysteine residues(R-S-S-
R)
• These bonds contribute to the correct folding of protein as
other elements of secondary structure.

13. Lipidation
• Attachment of lipid group (fatty acid)covalently to protein
• Play role in cellular localization, targeting signals, membrane
structure and protein interactions.

14. DETECTION TECHNIQUE??
• Mass spectrometry
• HPLC analysis
• Incorporation of radioactive group by addition to growing cell
(75se labelling)
• Antibody cross reactivity(ab against phosphotyrosine)
• Gel electrophoresis.

15. REFFRENCES
• https://en.wikipedia.org/wiki/Post-
translational_modification#:~:text=Post%2Dtranslational%20
modification%20(PTM),of%20proteins%20following%20prot
ein%20biosynthesis.&text=Other%20forms%20of%20post%2
Dtranslational,removing%20the%20initiator%20methionine%
20residue.
• https://www.nature.com/articles/cr2013151
• https://microbenotes.com/post-translational-modification/