Ctb Exam 1 Lectures 4 - 5

Front 1

lipid raft

Back 1

thicker region of the plasma membrane that contains a lot of glycosphingolipids and contain receptors for toxins

Front 2

integral protein diseases

Back 2

blood clotting issues, cancer - integrin

myasthenia gravis - AChR - excitation responses affected

cystic fibrosis - CFTCR - Cl- channel - misfolded protein can't make it to cell surface

Front 3

peripheral protein diseases

Back 3

muscular dystrophy - dystrophin

cardiac arrhythmias - ankyrin - ion channels in cardiac membrane

sickle cell disease - spectrin

proteinuric kidney disease - dynamin - cell permeability

Front 4

GPI linked protein disease

Back 4

cancer - Ras

Front 5

How does integrin link actin to the ECM?

Back 5

2 methods

One end of integrin is bound to the ECM and passes through the plasma membrane. It binds to Talin, which forms a complex with Vinculin and together they bind Actin.

Integrin again binds to ECM and passes through PM but binds to alpha actinin which then binds actin.

Front 6

How does blood clotting work and how does Integrilin prevent the process from taking place?

Back 6

Fibrinogen normally binds to integrilin molecules on 2 different platelets, forming a clot. Integriling (RGD tripeptides) bind to Integrin, thus blocking Fibrinogen and preventing the blood from clumping.

Front 7

Describe the Spectrin membrane skeleton in RBCs

Back 7

Spectrin molecules (long thin proteins) bind to Ankyrin (globular proteins) and actin. Ankyrin interacts with Band 3, and integral membrane protein, to connect this meshwork to the PM. Actin also binds to Band 4.1 which binds to glycophorin, an integral membrane protein.

Front 8

basic mechanism of muscular dystrophy

Back 8

Cells that lack dystrophin leak MG53, a key component of cell membrane repair, when they are damaged, leading to degeneration of muscle

Front 9

N cadherin

Back 9

provides signal for neurite formation

Front 10

Zonula Occludens (Tight Junction)

Back 10

prevent intercellular transport

transmembrane proteins = claudin and occuldin (claudin is a water channel woven within occludins)

ZO-1 and ZO-2 are cytoplasmic proteins that bind to Actin

Front 11

Zonula Adherens / Adheren Junctions

Back 11

transmembrane protein = cadherin

cytoplasmic proteins = catenin --> vinculin --> alpha actinin which bind actin filaments

Front 12

Macula Adherens / Desmosome

Back 12

found in areas with a lot of stress like cardiac muscle and skin

transmembrane proteins = desmoglein and desmocollin

attachment plaque is made of desmoplakin and plakoglobin which binds intermediate filaments

Front 13

Gap Junction

Back 13

Consists of connexons, which are made of 6 cylindrical subunits called connexins

cytoplasmic proteins = ZO-1 and Drebrin that bind actin

Mutations:
Connexin 26 - inherited deafness
Connexin 50 - cataracts in lens

Front 14

Hemidesmosome

Back 14

adhere epithelial cells to basal lamina

transmembrane proteins = integrin and BP 180

cytoplasmic proteins = BP230 and plectin which bind intermediate filaments

Front 15

Kartagener's syndrome

Back 15

a tyope of Primary Cilia Dyskinesia

absence of dynein arms on microtubules leads to immotile cilia in the respiratory tract

Front 16

primary cilia

Back 16

sensors of fluid flow

passive bending as a result of fluid flow in a kidney tubule opens polycystin 1&2, mechanoreceptor calcium channels

Front 17

major functions of cell membranes

Back 17

structure, protection, activation of cell, transport, cell to cell interaction

Front 18

functions of integral membrane proteins

Back 18

channel (pore), transporter (carrier), receptor, enzyme, cytoskeleton anchor, cell identity marker

Front 19

subdomains of ER

Back 19

smooth, rough, nuclear, export sites

Front 20

unfolded protein response

Back 20

series of signaling cascades that respond to environmental stress and developmental cues - slow down translation and increase molecular chaperones that assist in correct folding of proteins

Front 21

chronically activated UPR

Back 21

occurs in conditions of low O2, high or low blood glucose - leads to inflammation in obesity and atherosclerosis, diabetes, cancer

Front 22

enlarged, dilated cisternae of ER

Back 22

hydropic swelling of liver cells due to toxic injury

Front 23

progeria

Back 23

normally lamin A is farnesylated and then the lipid is cleaved off but in progeria the cleavage site is deleted so lamin becomes progerin --> abnormal nuclear morphology, progerin in mitotic cytoplasm, binucleation

Front 24

post translational targeting / import

Back 24

proteins are assembled on free ribosomes and are distributed to cytoplasm, nucleus, peroxisome, mitochondria

Front 25

co-translational targeting / import

Back 25

proteins are made on RER ribosomes and are distributed to the ER, Golgi, plasma membrane and lysosome

Front 26

How are proteins targeted to the ER?

Back 26

Signal Recognition Particle (SRP) binds to signal sequence of mRNA, arresting translation. SRP interacts with a docking protein on the ER membrane and is then released, allowing translation to continue. Signal sequence interacts with translocator channel protein so ribosome - ER interaction is stabilized. Signal peptide is cleaved off by signal petidase and is digested. Protein is released into lumen of ER.

Front 27

actin mRNA zip codes

Back 27

3' untranslated sequence - needed to localize actin mRNA to specific regions of the cell - can block this polarization using oligonucleotides

Front 28

Cystic Fibrosis Transmembrane Conductance Regulator

Back 28

Cl- channel in epithelial cells

in CF, it gets misfolded so it can't reach the membrane

can add chaperones in the hopes of getting it to properly fold - BiP (binding protein)

Front 29

Smooth ER functions

Back 29

conversion of glycogen to glucose in the liver, storage of calcium in the sarcoplasmic reticulum, detoxification via oxidative enzymes like P450s, synthesis of steroid hormones in gonads and the adrenal cortex

Front 30

COPII

Back 30

associates with the membrane at ER export sites to facilitate budding

coat is assembled via Sar1, Sec 23 - Sec 24, Sec 13 - Sec 31

concentrates cargo and bends ER membrane to create transport vesicle for delivery to Golgi (anterograde)

Front 31

parts of the Golgi

Back 31

ERGIC (ER - Golgi Intermediate Compartment)
cis face
medial face
trans face
trans Golgi Network

Front 32

I Cell Disease

Back 32

defect in adding Mannose 6 phosphate to lysosomal enzymes ==> there's a build up of substances in lysosomes and the proteins are excreted instead of imported into lysosome

Front 33

Vesicular tubular cluster

Back 33

aka ERGIC

mediates trafficking between ER and Golgi - facilitates sorting of cargo

Front 34

COPI

Back 34

coats vesicles that move Golgi to ER (retrograde)

Front 35

V SNARES and T SNARES

Back 35

transmembrane proteins on vesicles and target sites that bind together, leading to immediate fusing of membranes

can be destroyed by toxic enzymes, affecting exocytic processes which can lead to failure of muscle to contraction

Front 36

types of endocytosis

Back 36

phagocytosis, macropinocytosis, clathrin mediated, caveolin mediated, plain ole pinocytosis

Front 37

Familial Hypercholesterolemia

Back 37

High serum levels of LDL due to a mutation in binding to receptors (normally found in coated pit regions of the plasma membrane)

Front 38

clathrin mediated endocytosis

Back 38

AP2 binds to transmembrane receptor and clathrin to form a lattice structure. Dynamin helps pinch off the pit. Inside the cell, clathrin and adaptins disassemble via HSC70 and auxillin (accessory molecules) and are recycled.

Front 39

caveloae

Back 39

invaginations in membrane - lipid subdomains rich in sphingolipids and cholesterol

coated with caveolin protein

preferred means of entrance by pathogens because it doesn't feed into lysosomal pathways