iRAT questions week 1:

Cell motility in physiology and pathology

iRAT questions week 1:

• Fibroblasts seem to lay as single cells embedded into the extracellular matrix

(ECM) present in connective tissue. However, the fibroblasts do make cell- cell junctions between each other. Which cell-cell junctions are present between fibroblasts? —> gap junctions. They are single cells that produce the proteins of the ECM. The gap junctions allow the exchange of small molecules

• Hemidesmosomes are formed by ___ and connect an epithelial cell with ___ . —

> integrins, the basement membrane

• Integrins are cell-ECM adhesion receptors and can bind to many different

ECM molecules. Which of the following is NOT an ECM protein, and therefore NOT an integrin ligand? —> lamin. It is in the nuclear envelope. Laminin is located in the basement membrane.

• Cadherin-cadherin and integrin-ECM interactions differ in terms of binding

strength or active/inactive molecular state, with possible consequences for migration. Which of the following statements is NOT true? —> Cadherins can bind to other cadherins as well as to ECM molecules of the basement membrane to generate epithelial stability.

• For 2 epithelial cells to separate from each other, E-cadherin may be downregulated or degraded. This may allow cell migration across other epithelial cells or away from the epithelium.• In fibroblasts, integrins may be downregulated or degraded. This may change cell migration rates within ECM.• Integrin activation/ de-activation events are sufficient to change cell- ECM adhesion strength. This may change cell migration rates.

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• Which fibrillar protein does not form the cells cytoskeleton? —> collagen

fibers. Cytoskeleton: Intermediate filaments, Actin cytoskeleton, Microtubules

• What is the correct order of the migration steps of a mesenchymal cell

moving over a 2D surface? —> Protrusion, adhesion, contraction, rear retraction

• Which of the following state to about the contraction of skeletal muscle is

correct? —> The power stroke of skeletal muscle contraction occurs when the myosin head releases Pi.

• Ca

2+ released into a myofibril by the action of a nerve impulse binds to a site on ___ , in order to initiate skeletal muscle contraction. —> troponin

• Which of these statements about the protein calmodulin is correct? —>

Protein in the cytoplasm of smooth muscle that binds calcium. Calcium-bound calmodulin interacts with myosin light chain kinase and phosphorylates myosin light chain leading to actin contraction.

• Which out of the following statements is true about G-protein coupled

receptors? —> The N-terminal chain is extracellular and C-terminal chain is intracellular

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Lecture I: intracellular determinants of migration

Actin filament-based structures

• Migration-associated actin filaments

• Molecular actin filament organization/dynamics

Actin globular filaments form dynamic actin filaments 3 / 4

Really energy consuming process: up to 50% of total ATP consumption my be used

for actin polymerization.

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