Cell biology IV Flashcards
What protein is involved in constructing and shaping of the sER?
Atlastin
What class of protein is atlastin?
GTPase
What happens to the ER and Golgi in response to an abundance of atlastin?
1) Increased ER membrane fusion2) Absence of Golgi
What happens to the ER as a result of atlastin deficiency?
ER fragmentation
ER fragmentation occurs in response to a deficiency in what protein?
Atlastin
Hereditary spastic paraplegia is caused from a deficiency in what protein?
Atlastin
What condition arises due to atlastin deficiency?
Hereditary spastic paraplegia
What are symptoms of hereditary spastic paraplegia?
1) Leg stiffness2) Gait disturbances (stumbling, tripping)
Proteasomes make up what percentage of cellular proteins?
1%
Are proteases ATP-dependent?
Yes
Where are proteasomes located in the cell?
Cytoplasm and nucleus
Proteasomes are involved in proteolysis of what types of proteins?
1) Regulating proteins (e.g. cell cycle, txn, apoptosis)2) Malformed, denatured, damaged proteins3) Antigenic proteins (cleaved and presented to T cells)
Are proteasomes ubiquitin-dependent, -independent, or both?
Can be either (both)
Proteasomes are inhibited by what type of molecule?
Abnormal prion proteins
What effect to abnormal prion proteins have on proteasomes?
Inhibition
Defective proteolysis by proteasomes is causative in what diseases?
Parkinson’s disease, cystic fibrosis
What is the function of bortezomib in cancer cell therapy?
Bortezomib partially inhibits proteasomes, thus decreasing the degradation of pro-apoptotic factors
In polarized cells, where is the Golgi located?
Between the nucleus and apical cytoplasm
When is a negative Golgi image seen?
In active protein-secreting cells
What is a negative Golgi image?
A pale-staining area of cytoplasm seen in H&E staining (neither acidophilic nor basophilic)
In which direction is the cis-Golgi oriented in the cell?
Presents toward the transitional ER where transport vesicles are forming
What is formed from the trans-Golgi?
1) Secretory granules (vesicles)2) Lysosomes3) Membrane protein-transporting vesicles