Post translational modification of hydroxylysine and hydroxyproline is by
Correct Answer: Vit C
Description: Ans: a (Vit C) Ref: Vasudevan 4th ed/p.415Post translational modification:-* Gamma carboxylation of glutamic acid residues of prothrombin under the influence of vitamin K.* Hydroxylation of proline and lysine in collagen with the help of Vitamin C* C- terminal amidation and cyclisation of N-terminal amino acid of TRH* Phosphorylation of hydroxyl groups of serine, threonine or tyrosine by kinases.eg. glycogen phosphory- laseCotranslational glycosylation, whereby carbohydrates are attached to serine or Threonine residues* Methylation of lysine, Histidine and Arginine residues eg. Histones* Acylation eg.myelin proteolipid or transferring receptor.Post transcriptional modification:-* 5' capping: - this is the first of the processing reactions for hn RNA. 7-methyl guanosine is attached 'backwards' to the 5' terminal of the mRNA. This serves to stabilise the mRNA.* Addition of poly-A tail (3' polyadenylation): About 40-200 adenine are attached to the 3' end of the mRNA. These tails help to stabilize the mRNA and facilitate its exit from the nucleus. After mRNAenters the cytosol, the poly-A tail is gradually shortened.Removal of introns (splicing):- Introns or intervening sequences that do not code for protein are removed. This splicing occurs in the nucleus and serves to bring the exons together. After removal of the introns, the mature mRNA molecules leave the nucleus.
Category:
Biochemistry
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