POST TRANSLATIONAL MODIFICATION (PTM) SIMPLE & BASIC CONCEPT

1. BY
A.MANOJ KUMAR

2.  It is a chemical modification of a protein after its
translation.
 It takes place at certain amino acids residues after
the protein is synthesized.
 Post Translational Modification are essential for
normal functioning of the cell.
 It necessary for
 Stability of protein
 Biochemical Activity
 Protein Targeting (protein localization)
 Protein signalling(protein-protein interaction)

3.  PTMs occur in Golgi Apparatus and Endoplasmic
Reticulum
MODIFICATION
 Modification involving peptide bond cleavage
 Modification of Amino acids
 Protein folding and chaperones
 Subunit Aggregation
 Protein Folding

4.  It is specific and well regulated
 Enzymatic and non – enzymatic
 Precursor protein(inactive)-Mature active ptn
 The amino acids residues are removed one by one
either from N-terminus or C-terminus end, with
the help of the enzyme exopeptidase

6. PHOSPHORYLATION
 Addition of Phosphate group to serine,threonine
and tyrosine
LIPIDATION
 Addition of lipid molecule such as fatty acids to
the protein chain
UBIQUITINATION
 Addition of Ubiquitin,to a lysine residue of a
target protein, marking it for destraction.

7. ACETYLATION
 Addition of Acetyl group to the N-terminus of the
protein to increase the stability
GLYCOSYLATION
 Addition of sugar molecule to the ‘N’ or ‘O’ atom
in an amino acid side chain
METHYLTION
 Addition of methyl group to the amino acid

8.  Many enzyme function only when it associated
with co-factor or prosthetic group
 The prosthetic group are
Biotin,FAD,Haem,Pantothemic acid
 The tertiary and quaternary structure of protein is
attained only when it complexed with some co-
factor
 Iron in case of Haemoglobulin
 Mg²+ in case of chlorophyll

9.  Signal molecules are added or removed from the
N-terminus end off the protein for the
transportation to their specific destination
 Once a protein has reach its destination the signal
molecules is removed

10. MODIFICATION
PHOSPHORYLATION
GLYCOSYLATION
ACYLATION
ALKYLATION
HYDROXYLATION
AMINO ACIDS
Ser,Thr,Tyr
Asn,Ser,Thr
Asn,Gln,Lys
Lys, Arg
Pro, Lys

11.  Chaperon are proteins that facilate folding of other
proteins
 Chaperon first discovered in drosophila
 They are also called as heat shock protein HSP70
AND HSP 60
FUNCTION
 It prevents the formation of unwanted interaction ,
that do not provide biological activity
 Stabilises the interaction
 Avoids improper folding ,aggregation and
precipitation of protein

13.  The protein consist of Exteins and Inteins
 An Inteins is a segment of a protein that is able to
excise itself and join the remaining portion with the
help of peptide bond
 The protein Splicing is required for convention of
inactive protein precursor into biologically active
protein
 It is found in bacteria,Eukaryotes and viruses.