Cell Compartmentalisation, Flashcards
Mitochrondria and pm
Involved in inclusion of pm
Pinching of specialised pm
Cause formation of organelles interior - similar to exterior of cell
Organelles involved in cycles of membrane budding and fusion
Golgi, rer, vesicles, ser, peroxisomes, lysosomes, endosomes,
4 distinct families of intracellular compartments?
Nucleas
Organelles Involed in secretory/endosomes pathway
Mitochrondria - fusion and fission replication - maternal dna - circular
Plastids (plants)
Nuclear por proteins modified with ?
O-N-acetyl glucosamine - post translational modification - RER
Why is GlcNAc important?
Modification of protein integrates metabolic information
Amount dependant on Biosynthetic pathway
Hexamine biosynthetic pathway?
Glucose, glucose 6 p, fructose 6 p, (aa met) glucosamine 6 p, n acetylglusosamine 6 p, n acetyl glucosamine 1 p, (nucleotide met) UDP-N acetyl glucosamine
Stressfull stimuli lead to increase of the ….
O N acetyl glucosamylation of Nuclear pore proteins (NUP)
Examples of stressfull stimuli O-GlyNAc ylation of NUPs
Heat shock, uv radiation, hypoxia, oxidative/reductive stress, ethanolic stress, trauma haemorrhage, cell cycle arrest, osmotic stress
NUP stim. What? (2)
Gene expression and cell cycle genes
Example of NUP
Mtor and MP153 - located at npc - associated w/ active transcription - filaments - translocated mrna into cytosol
Tumour? And genes
Mutation of protooncogene - oncogene - uncontrolled cell division
NUP98 is example of?
Gene fusions (bind to other genes) + hematopoietic malignancies
Hematopoeitic malignancy!
Change in myeloid linage - impaired t,b cell differentiation
Different cells have different amount of organelles
Therefore different genes switched on/off.
Eg pancreas - hormones - RER - 60% pf total plasma membrane
Ribosomes with mrna that codes for secretory proteins?
Binds to rer via ribophorins
Nuclear and peroximal proteins?
Other example of proteins folded?
Folded specifically - cytoplasm
To peroxisomes and npc ( receptor mediated)
Chloroblast - specific folding of proteins
ER signal?
Specific sequence KDEL n terminus (20-24 aa, hydrophobic)
Bind to srp - er membrane
Ribosome bind to er membrane
Signal peptidase cleaves specific sequence
Biogenesis pathway of mito proteins?
Nascent protein - precursor protein - TOM - intermembrane space
PROTEASOMES?
20-24 protein subunits
Cylindrical
Hydrolyse incorrectly folded proteins
Links to incorrect protein via ubiquinated protein
Ubiquinated protein
9000aa,
Cytosol
Link proteasome enzyme to incorrectly folded protein
RER incorrectly folded proteins
Unfolded protein response (degradation pathway) -> to cytoplasm
Ubiquinated protein
Proteasome (degradation)
Molecular chaperones?
Assist protein folding in ER - golgi complex - ecm
Calnexin (membrane bound protein-hydrophobic) and
calreticulin cycle (luminal protein - soluble in cytosol of rer)
Make more reliable and efficient
Cycle of glycosylation and deglycosylation ->
Detect folding of protien
Protein point mutation?
Change : base sequence, primary, secondary, tertiary structure.
protein incorrectly folded. Irreversible.
Protein folding
Protein to lowest energy conformation - stable.
Interact with other molecules - changes - crucial for function
Incorrect folding of proteins leads to?
Amyloid fibrils accumulation.
Eg. Amylodogenic intermediate - ring shaped early aggregate - protofibrils - mature fibrils - lewy bodies
Lewy bodies
Neurons - amyloid fibril accumulation - incorrect protein.
Faster produced than protein degradation pathway of protein unfolded protein response .
Parkinsons disease
Leukaemia?
Ig light and heavy chains - incorrect - not secreted by cell - problem with immune response
6 inclusion pathiogenesis. Name, site and disease associated
Levy bodies - neurons cyto - parkinsons
Huntingdon bodies - neuron nuclear - huntingtons disease
Hiramo bodies - neuron - neurodegenerative
Collins bodies - neuron - familial presenile genitris
Neurofibrillar tangles - neurons nuclear - alzhiemers, aging, dementia + other cerebral disorders
