Rr Biochem: Chapt. 3 Membrane, Signal Transduction

Front 1

Is cholesterol present in the inner or outer or both leaflets of the cell membrane?

Back 1

both

Front 2

Which phospholipids are present in the outer and the inner leaflets of the erythrocyte plasma membrane?

Back 2

outer: PC (phosphatidylcholine), sphingomyelin.
inner: PS (phosphatidylserine), PE (phosphatidylethanolamine)

Front 3

proteins constitute __% by weight of most cellular membranes

Back 3

40-50%

Front 4

List 4 factors that decrease membrane fluidity:

Back 4

long-chain saturated fatty acids, fewer cis unsaturated fatty acids, low temperature, cholesterol

Front 5

give an example of an antiporter in the erythrocyte membrane that facilitates the diffusion of 2 substances and functions in the transport of CO2 to the lungs

Back 5

Cl-/HCO3- exchange protein facilitates diffusion of Cl- and HCO3-

Front 6

The 3Na/2K-ATPase pump is inhibited by drugs such as ___, and enhanced by ___.

Back 6

inhibited by cardiotonic steroids (digitalis, ouabin), enhanced by albuter

Front 7

Which 2 pumps maintain low cytosolic Ca2+ concentration? What role do they play in muscle?

Back 7

1. Plasma membrane Ca2+-ATPase: present in most cells
2. Muscle Ca2+ATPase located in the sarcoplasmic reticulum of skeletal muscle.
Restoration of low cytosolic Ca2+ permits muscle to relax, and replenishes Ca2+ stores in the SR for triggering the next muscle contraction.

Front 8

How does tissue hypoxia affect Ca2+ levels and effect does this have on the cell?

Back 8

hypoxia decreases ATP production, which impairs the Ca2+ ATPase pump, allowing Ca2+ into the cell. Ca2+ activates various enzymes (phosphlipases, caspases) that lead to irreversible cell damage.

Front 9

Two organs were Na+-linked symporters are important.

Back 9

Na+/glucose symporter (SGLUT1) mediates absorption of glucose by epithelial cells of kidney tubules and intestine. Other cotransport carrier proteins may couple Na+ with amino acid transport.

Front 10

Apart from the ___ pump, digitalis also inhibits the ____ antiporter in cardiac muscle cells.

Back 10

Na/K-ATPase; Na-linked Ca2+ antiporter. [Na-linked Ca2+ antiporter is responsible for maintaining low cytosolic Ca2+ (3 Na+ enters, 1 Ca2+ exported).]

Front 11

Cystic Fibrosis: which transporter is defective and how does this affect secretions in the skin, airways, and pancreatic and bile ducts.

Back 11

AR defect in CFTR, a Cl- ATPase pump in epithelial cells of the lungs, pancreas, intestines, skin. Defect results in high NaCl in sweat, and viscous mucus that obstructs the airways and pancreatic and bile ducts. Lungs are susceptible to recurrent Pseudomonas infection.

Front 12

Cystinuria is an autosomal ___ disorder characterized by defects in renal tubule transporter that mediates the reabsorption of ___ amino acids (list 4). Clinical features: ___ and excess____ amino acids in the ___

Back 12

AR defect in renal tubule transporter that mediates reabsorption of dibasic amino acids (Cystine, Arg, Lys, Ornithine). Clinical features: cystine kidney stones (hexagonal shaped) and excess dibasic amino acids in the urine

Front 13

Hartnup's disease is caused by an autosomal __ defect in the carrier protein that mediates ___ and ___ absorption of ___ ___ ___. Specifically, impaired absorption of ___ reduces the synthesis of ___, which causes pellagra-like symptoms (__, __, __).

Back 13

Hartnup's disease is caused by an autosomal __ defect in the carrier protein that mediates intestinal and renal absorption of neutral amino acids. Specifically, impaired absorption of Tryptophan reduces the synthesis of niacin, which causes pellagra-like symptoms (diarrhea, dermatitis, dementia)

Front 14

Familial hypercholesterolemia is an autosomal ___ disease characterized by a lack of receptors for ___. The resultant high plasma ___ leads to premature ___ and risk of ___ and ___ at an early age.

Back 14

Familial hypercholesterolemia is an autosomal dominant disease characterized by a lack of receptors for LDL. The resultant high plasma cholesterol leads to premature atherosclerosis and risk of acute MI and stroke at an early age.

Front 15

What are the locations for the receptors for: 1) steroid hormones; 2) thyroxine; 3) retinoic acid

Back 15

1) cytosol. 2) and 3) nucleus

Front 16

G-protein coupled receptors are ___meric proteins. Transmembrane portion consists of __ (what kind of protein structural motif)? Cytosolic domain interacts with ___.

Back 16

monomeric, containing 7 trnasmembrane alpha-helices. Cytosolic domain itneracts iwth trimer G protein.

Front 17

When bound by ___, G protein is in the ___ state, and the __ subunit either stimulates or inhibits an associated ____.

Back 17

When bound by GTP, G protein is in the active state, and the alpha subunit either stimulates or inhibits an associated effector protein.

Front 18

The receptors for epinephrine (beta receptors), and ___ are coupled to the G_ protein and signals through the second messenger: ___.

Back 18

glucagon, Gs, cAMP

Front 19

In this disease, ___, sustained ___ stimulation cause beta-adrenergic receptors to undergo ___ (reduction in physiological response upon repeated stimulation). The phosphorylated receptor cannot interact with ___.

Back 19

In pheochromocytoma, sustained epinephrine stimulation cause beta-adrenergic receptors to undergo accommodation. The phosphorylated receptor cannot interact with Gs protein.

Front 20

Activation of Gq protein by receptors of the hormones (__, __, ___) cause the stimulation of ___, which cleaves __ to yield __ and __.

Back 20

Activation of Gq protein by oxytocin, AngII, vasopressin (V1 receptor) cause the stimulation of phospholipase C, which cleaves PIP2 to yield IP3 and DAG.

Front 21

___ (second messenger) causes Ca2+ release from the ER, leading to the formation of ___ complex, which in turn activates ___ to induce smooth muscle contraction.

Back 21

IP3 causes Ca2+ release from the ER, leading to the formation of Ca-calmodulin complex, which in turn activates myosin light chain kinase to induce smooth muscle contraction.

Front 22

__ activates protein kinase C, which is recruited to the plasma membrane by elevated cytosolic __.

Back 22

DAG, Ca2+

Front 23

Hormone binding to ___ leads to receptor autophosphorylation.

Back 23

receptor tyrosine kinase

Front 24

Binding of growth factors to their __meric receptors causes the receptors to __, eventually leading to activation of ___ (a type of G protein) and the ___ pathway.

Back 24

monomeric; aggregate, Ras; MAP kinase (eg. epidermal GF, PDGF)

Front 25

Insulin receptor is a ___ that uses ___ to activate 2 pathways that mediate the long-term and short-term effects of insulin, respectively (name and describe the effects of the pathways):

Back 25

Insulin receptor is a receptor tyrosine kinase that uses IRS1 to activate 2 pathways that mediate the long-term and short-term effects of insulin, respectively (name and describe the effects of the pathways): 1) RAS-dependent: increase glucokinase synthesis in liver; 2) Ras-independent pathway acts through protein kinase B, leading to increased glucose uptake by muscle and adipocytes, and stimulate glycogen synthase.

Front 26

Cholera, ___ E. coli, and __ toxins catalyze ___ ___ of the __ subunit of G proteins. The first 2 permanently activate __, which activates __ __ leading to __ diarrhea. Pertussis toxin __ Gi protein by __ ___, which activates __ __, causing __ __ in the respiratory tract.

Back 26

Cholera, enterotoxigenic E. coli, and pertussis toxins catalyze ADP ribosylation of the alpha subunit of G proteins. Cholera and ETEC permanently activate Gs protein, which activates adenylate cyclase, leading to secretory diarrhea. Pertussis toxin inactivates Gi, which activates adenylate cyclase, causing mucus secretion in the respiratory tract.

Front 27

__ is the most commonly mutated protooncogene, and is implicated in __, __, __, and __ cancer.

Back 27

Ras; pancreatic, colon, endometrial, thyroid

Front 28

Ephedrine is a general agonist of ____ receptors, producing ___ (nasal decongestant)

Back 28

alpha1-adrenergic, vasoconstriction

Front 29

Albuterol and terbutaline are relatively selective agonists of __ receptors, causing ___.

Back 29

alpha2-adrenergic receptors, causing smooth muscle relaxation

Front 30

beta-blockers: name 2 selective and 2 non-selective drugs

Back 30

selective: metoprolol, atenolol.

non-selective: propanolol, timolol

Front 31

Antipsychotics such as __ and __, block dopamine D2 receptors.

Back 31

chlorpromazine, haloperido\l

Front 32

Gs protein: list its function and coupled receptors

Back 32

Gs stimulates adenylate cyclase, which icnreases cAMP. Dopamine (D1), epinephrine (b1, b2), glucagon histamine (H2), ADH (V2).

Front 33

__ inhibits adenylate cyclase and is coupled to dopamine (D2) and ___ (alpha_) receptors.

Back 33

Gi; epinephrine (alpha2)

Front 34

Gq protein: lists it function and coupled receptors

Back 34

stimulates phospholipase C. AngII, epinephrine (a1), oxytocin, ADH (V1)

Front 35

__ protein stimulates cGMP phosphodiesterase and is coupled to __.

Back 35

Gt (transducin), rhodopsin

Front 36

GLUT1 is located in __ cells (but not __ and __ cells). Transports __ (with __ affinity) and __ but not __.

Back 36

most cells (but not kidney and small intestinal epithelial cells). Transports glucose (with high affinity) and galactose but not fructose.

Front 37

GLUT2:
- Liver: at __ blood glucose, it mediates uptake of glucose (with __ affinity), __ and __.

- pancreatic beta-cell: act as __ __

- Intestine and ___: __ glucose on the ___ side.

Back 37

Liver: at high blood glucose, it mediates uptake of glucose (with low affinity), galactose, and fructose.

beta-cells: glucose sensory

Intestine and kidney: reabsorbs glucose on the basolateral side.

Front 38

GLUT3 is located in the __, __, and __. Transports __ (with __ affinity) and __ but not __.

Back 38

neurons, placenta, testes. Transports glucose (with high affinity) and galactose but not fructose.

Front 39

Insulin induces translocation of __ from the ___ ___ to the cell __ to mediate glucose uptake. It is located in cardiac and skeletal muscles, and adipocytes.

Back 39

Insulin induces translocation of GLUT4 from the Golgi Apparatus to the cell surface to mediate glucose uptake. It is located in __ and __ muscles, and __.

Front 40

GLUT5 transports __ (__ affinity) and is located in (name 6)

Back 40

fructose (high affinity). small itnestine, sperm, kidney, brain, muscle, adipocytes

Front 41

GLUT7 is located in the membrane of the __ in __. It transports free __ produced in the ER by __ into the cytosol for secretion into blood by
__.

Back 41

GLUT7 is located in the membrane of the ER in hepatocytes. It transports free glucose produced in the ER by glucose-6-phosphatase into the cytosol for secretion into blood by GLUT2.

Front 42

SGLUT1 is a ___ symporter that is located in the __ and __. It couples __ influx to cotransport ___ or ___.

Back 42

Na/K symporter that is located in the small intestine, and kidney. It couples Na+ influx to ccotransport glucose or galactose.

Front 43

GLUT3 is located in the __, __, and __. Transports __ (with __ affinity) and __ but not __.

Back 43

neurons, placenta, testes. Transports glucose (with high affinity) and galactose but not fructose.

Front 44

Insulin induces translocation of __ from the ___ ___ to the cell __ to mediate glucose uptake. It is located in cardiac and skeletal muscles, and adipocytes.

Back 44

Insulin induces translocation of GLUT4 from the Golgi Apparatus to the cell surface to mediate glucose uptake. It is located in __ and __ muscles, and __.

Front 45

GLUT5 transports __ (__ affinity) and is located in (name 6)

Back 45

fructose (high affinity). small itnestine, sperm, kidney, brain, muscle, adipocytes