Exam1 study guide

Question 1

nuclear transport wiht regards to huntingtons

Answer 1

-this mutation is the addition of a glutamine residue which plays a role in increased huntingtin import into the nucleus

Question 2

what will we learn from progeria

Answer 2

a lot about aging and cardiovascular disease

Question 3

importins

Answer 3

chaperon proteins that bind to NLS’s and escort proteins into the nucleus

Question 4

SINEs

Answer 4

small molecules tht bind to and block the pocket on exportin 1 used by tumor supressor.
-this inhibits cell deivision and is a target for cancer drugs

Question 5

Key points about export

• NES
• selectivity of an exportin
• exportin 1

Answer 5

• proteins and ribonucleoproteins have nuclear export signals that are recognized by exportins. Exportins recognize a specific 5’-Gppp site on the nuclear pore and bind to it
• each exportin has a selective set of cargos
• exportin 1 is for anti-tumor proteins

Question 6

nuclear membrane assembly/disassembly

Answer 6

• lamins are responsible for connnecting chromatin to the nuclear membrane
• during interphase, lamins are dephosphorylated, leaving the nuclear membrane intact
• early in mitosis, lamins are phosphorylated by a kinase, causing the chromatin-nuclear mem connection to break and the nuclear membrane to disassemble
• late in mitosis, a phosphotase removes the phosphates from the lamin and the chromatin are allowed to join the nuclear membrane again the membrane itself reforms

Question 7

Niemann pick

Answer 7

• he thinks this will be the next disease to teach us a lot about lipid trafficking in cells and about other diseases
• it is NOT a sphingolipid disorder, we actually do not know that enzymes and substrated involved yet

Question 8

plasma membrane composition

-lipid rafts

Answer 8

• asymmetrical
• lipid rafts are more rigid than the rest of the membrane because they are high in sphingolipids and cholesterol. They can move quickly in the membrane and are responsible for concentrating ligand-receptor complexes into clathrin coated pit regions and important for bringing together components of signal transduction pathways

Question 9

why is an asymmetrical membrane important

Answer 9

-the outer leaflet is generally much more fluid than the inner leaflet, allowing lipid rafts to rapidly concentrate ligand-receptor pairs at specific sites on the membrane for internalization

Question 10

sphingolipids and fusion

Answer 10

-they do not have fusogenis properties

Question 11

first LSD to be treated with enzyme replacement therapy

Answer 11

-Fabry’s disease and then Gaucher followed

Question 12

factors affecting membrane fluidity

Answer 12

• heat
• chain length
• double bonds
• cholesterol

Question 13

band 3

Answer 13

• the anion exchanger in RBC’s
• this protein has a membrane spanning region, binding sites for ankrin and glycolytic enzymes intracellularly and has an N-links oligosaccharide extracellularly

Question 14

functions of carbohydrates on the cell surface

Answer 14

• blood type antigens
• pathogen recognition sites
• reservoir for cytokines/growth factors

Question 15

how particles of different sizes get into the cell

Answer 15

• if it is a bacteria or bigger, it gets in via phagocytosis

- if its a virus or smaller, it gets in via RME (except HIV and measles get in via fusing with the mem)

Question 16

clathrins

Answer 16

involved in conentrating ligand-receptor complexes into specialized regions of the membrane called clathrin coated pits

Question 17

lipid rafts

Answer 17

-used to ferry ligand-receptor complexes to the clathrin coated pits

Question 18

endosomes

Answer 18

-what is created after clathrin coated pits invaginate and pinch off

Question 19

what must happen for an endosome to fuse with its target?

Answer 19

• it must lose its clathrin coat
• must be acidified by a membrane bound H+ ATPase
• not only does H+ allow fusion but also allows the receptor-ligand complex to seperate

Question 20

Phagocytosis

Answer 20

-Fc receptors on the surface of the pahgocytic cell recognize IgG moleculse on the particle to be phagocytosed

Question 21

tuberculosis

Answer 21

this pathogen is phagocytosed

Question 22

Tangier

Answer 22

• Chesepeak bay, consanguinity
• present with CHD and neurological problems
• swollen bright orange tonsels
• markedly reduced plasma levels of HDL
• gave us a great understanding of CHD
• gene involved is part of the ATP binding cassette fam and responsible for reverse cholesterol transport
• if no LDL comes out of the cell, HDL is cleared to the lymph glands
• LDL that is not cleared builds up in the blood vessel wall
• helped show that the most common lipoprotein defect is reduced HDL

Question 23

what determines if the protein will be translated on the ER or in the cytoplasm?

Answer 23

• the first 20-25 aa’s which is where the signal peptide resides
• if there is a signal peptide then it will be taken to the ER, if there isnt one, it will stay in the cytoplams for translation

Question 24

proteins translated in the cytoplasm can go to

Answer 24

• peroxisome
• nucleus
• cytoplasm
• mitochondria

Question 25

proteins translated on the ER can go to

Answer 25

• ER
• secreted
• plasma membrane
• golgi
• lysosome

Question 26

I cell disease

Answer 26

• taught us the role of mannos 6 P in targetting the lysosome and led to our current understanding of organeller genesis
• defective enzyme is one which phosphorylates the 6 position of specific mannos residues
• under a microscope, cells with I cell disease appear to have dark, inclusion bodies where the lysosome are filled with biological material

Question 27

sequences that target proteins to the:

• peroxisome
• nucleus
• lysosome
• mitochondria

Answer 27

• peroxisome: three AA, SKL sequence
• NLS is a 5-6 basic AA sequence
• lysosome: mannose-6-P, this is the only nonpeptide targetting sequence
• mitochondria: a long, 75 AA sequence near the N-terminal end of the protein