34 - Post-Translational Mod & Human and Chloroplast Genomes

34 - Post-Translational Mod & Human and Chloroplast Genomes

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Transcription initiation •Direct influence of A and R on initiation •Activators (A), repressors (R) and remodeling proteins and chromatin structure •Methylation •Hormones and other “external” signals RNA processing •Alternative splicing and trans-splicing •polyadenylation Transport through the nuclear pore Posttranscriptional / pretranslational control (events on/with mRNA before ribosomes) •Localization of mRNA •RNA editing •Post-transcriptional silencing by siRNA or miRNA •Translational control switch •RNA stability (degradation and stabilization) Translational control (mRNA/ribosomes) •Phosphorylation of translation initiation factors •Upstream AUG codons •IRES Protein activity control Posttranslational modification and transport Control of gene expression: overall
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
, possible cleaving as wel l Protein activity control First step: posttranslational modification and transport
Background image of page 2
Protein modifications Modifications necessary for transport from the cytoplasm •Proteins that are membrane bound or are destined for secretion (e.g. TFs and protein hormones) are synthesized by ribosomes associated with the membranes of the endoplasmic reticulum (ER). The ER associated with ribosomes is termed rough ER (RER). •This class of proteins all contain a N- terminus - signal sequence or signal peptide; transport is co-translational Proteins destined for organelles: different signal sequences at N-terminus Proteolytic Cleavage Most proteins undergo proteolytic cleavage following translation. The simplest form - removal of the first methionine.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Acylation •In most cases acetyl group is added to the N-terminal amino acid (after first Met is removed) •Acetyl-CoA is the acetyl donor for these reactions. Glycosilation •Glycoproteins consist of proteins with covalently linked sugars (glucose, galactose, mannose, fucose, GalNAc, GlcNAc …) •Consensus AA for addition: Asn – X – Ser/Thr Methylation •Post-translational methylation occurs at lysine residues in some proteins •The activated methyl donor is S-adenosylmethionine. •Examples: calmodulin and cytochrome c Prenylation •Addition of the compounds derived from the cholesterol biosynthetic pathway •examples: oncogenic GTP-binding and hydrolyzing protein Ras
Background image of page 4
Phosphorylation •Post-translational phosphorylation is one of the most common protein modifications •Occurs as a mechanism to regulate the biological activity of a protein and as such – transient: phosphate (or more than one in many cases) is added and later removed (or transferred to other protein) •The enzymes involved: Kinases: transfer a phosphate group from a donor (usually ATP) to the acceptor (protein) Phosphorylases: transfer a phosphate group from an inorganic phosphate Phosphatases: remove phosphates •In animal cells serine, threonine and tyrosine are the amino acids subject to phosphorylation (-OH group - “phosphorylable” site) Sulfation •Sulfate modification of proteins occurs at
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 24

34 - Post-Translational Mod & Human and Chloroplast Genomes

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online