What is the role of CXCR4 in the data we studied in this project?

a) when inhibited, CXCR4 internalizes and binds to Rac

b) when activated, CXCR4 activates its bound G-protein which then dissociates, letting the beta-gamma subunits pass the information along

c) when activated, CXCR4 internalizes and binds to Rac

d) when inhibited, CXCR4 activates its bound G-protein which then dissociates, letting the beta-gamma subunits pass the information along.

This schematic represents early steps in signal transduction. Find the statement below that correctly explains a portion of the figure

[image]

a) in part 3, the heterotrimeric G-protein has dissociated

b) In part 1, the G-protein is activated

c) in part 2 a ligand has activated the GPCR

d) in part 4, the alpha subunit has reverted to being GDP bound

How does actin help a cell move?
a) F-actin localizes to the edges of lamellipodia

b) cortactin helps microtubules connect to the plasma membrane of the lamellipodia

c) Rho activates actin polymerization

d) Rac activates actin contractility at the trailing edge of the cell

Immunoblots, but not immunocytochemistry can show you:

a) if your protein and another protein colocalize in a cell

b) which splice variant of your protein is more abundant depending upon the experimental conditions

c) if your protein is more abundant under a particular condition 

d) if your protein is found in the nucleus

Which answer puts these proteins in the right order:

Rac, cortactin, G-bg (beta-gamma, but in the answers below, greek symbols are not allowed), CXCR4, CXCL12

a) CXCR4 -> CXCL12 -> Rac -> G-bg -> cortactin

b) CXCL12 -> CXCR4 -> Rac -> G-bg -> cortactin

c) CXCR4 -> CXCL12 -> G-bg -> Rac -> cortactin 

d) CXCL12 -> CXCR4 -> G-bg -> Rac -> cortactin 

Antibodies that recognize whether or not Rac is GTP bound quantifies how much activation has occurred.

[image]

a) only panel C uses an inhibitor of the GPCR

b) only panels A and B quantify cell shape changes

c) only panel C uses NIH-3T3 CM

d) only panels A and B test a SPECIFIC GPCR

Why might the investigators have used both MDA-MB-231 cells and MDA-MB-436 cell migration and invasion?

a) one provides the conditioned medium that gives migratory factors to the other

b) these exemplify metastatic vs. non-invasive breast cancer cells

c) using two metastatic breast cancer cell lines helps us know that the results are not just specific to one cell type

d) one cell type has a mutation in the GPCR's gene, making it unresponsive to chemokines

There are two rows, one labeled "1" in purple and the other labeled "2" in gold.  Which statement about the protein gel that was run to obtain these data is true?

[image]

a) GTP-Rac is only observed in cells treated with the receptor ligand

b) GTP-Rac is analyzed in stimulated cells, total Rac is examined from inhibited cells

c) The rows represent data from different protein gels

d) there was one gel that was blotted, but different antibodies were applied to the blot

What is the role of antibodies in the analysis of G-beta gamma and cell movement?

a) to examine distribution of cortactin after blockade of the signal transduction

b) to determine if the G-bg subunits have dissociated from the G-alpha subunit

c) to localize activated Rac within the cell

d) in western blots to examine Rac sub-cellular localization

Which of these correctly describe how a cell might adapt to an environmental chemical gradient in order to move in a particular direction (not randomly)?

a) the gradient-sensing G-proteins can respond by failing to dissociate

b) effectors detect the gradient chemical and become ligands that bind to the GPCR

c) the chemical gradient within a cell will differentially activate small, monomeric G proteins and kinases

d) The gradient-sensing receptor can relocalize to clump on one side of the membrane