The actin-nucleating protein formin has flexible “whiskers” containing binding sites that help recruit actin subunits in order to enhance polymerization by this protein. What protein would you expect to bind to these sites?

The rod photoreceptors in the eye are extremely sensitive to light. The cells sense light through a signal transduction cascade involving light activation of a GPCR that activates a G protein that activates cyclic GMP phosphodiesterase. How would you expect the addition of the following drugs to affect the light-sensing ability of the rod cells? Explain your answers. a drug that inhibits cyclic GMP phosphodiesterase a drug that is a nonhydrolyzable analog of GTP

Which of the following choices reflects the appropriate order of locations through which a protein destined for the plasma membrane travels?

In a cell that lacks cytosolic Hsc70: 

Activated protein kinase C (PKC) can lead to the modification of the membrane lipids in the vicinity of the active PKC. The Figure below shows how G proteins can indirectly activate PKC. You have discovered the enzyme activated by PKC that mediates the lipid modification. You call the enzyme Rafty and demonstrate that activated PKC directly phosphorylates Rafty, activating it to modify the plasma membrane lipids in the vicinity of the cell where PKC is active; these lipid modifications can be detected by dyes that bind to the modified lipids. Cells lacking Rafty do not have these modifications, even when PKC is active. Which of the following conditions would lead to signal-independent modification of the membrane lipids?    

v-SNAREs and t-SNAREs mediate the recognition of a vesicle at its target membrane so that a vesicle displaying a particular type of v-SNARE will only fuse with a target membrane containing a complementary type of t-SNARE. In some cases, v-SNAREs and t-SNAREs may also mediate the fusion of identical membranes. In yeast cells, right before the formation of a new cell, vesicles derived from the vacuole will come together and fuse to form a new vacuole destined for the new cell. Unlike the situation we have discussed in class, the vacuolar vesicles contain both v-SNAREs and t-SNAREs. Your friend is trying to understand the role of these SNAREs in the formation of the new vacuole and consults with you regarding the interpretation of his data.   Your friend has designed an ingenious assay for the fusion of vacuolar vesicles by using alkaline phosphatase. The protein alkaline phosphatase is made in a “pro” form that must be cleaved for the protein to be active. Your friend has designed two different strains of yeast: strain A produces the “pro” form of alkaline phosphatase (pro-Pase), whereas strain B produces the protease that can cleave pro-Pase into the active form (Pase). Neither strain has the active form of the alkaline phosphatase, but when vacuolar vesicles from the strains A and B are mixed, fusion of vesicles generates active alkaline phosphatase, whose activity can be measured and quantified (see Figure (a)).   Your friend has taken each of these yeast strains and further engineered them so that they express only the v-SNAREs, only the t-SNAREs, both SNAREs (the normal situation), or neither SNARE. He then isolates vacuolar vesicles from all strains and tests the ability of each variant form of strain A to fuse with each variant form of strain B, by using the alkaline phosphatase assay. The data are shown in the graph in Figure (b). On this graph, the SNARE present on the vesicle of the particular yeast strain is indicated as “v” (for the presence of the v-SNARE) and “t” (for the presence of the t-SNARE).   1) What do his data say about the requirements for v-SNAREs and t-SNAREs in the vacuolar vesicles? Describe the evidence supporting your answer. 2) Is it important to have a specific type of SNARE (that is, v-SNARE or t-SNARE) on each vesicle? Describe the evidence supporting your answer.

Describe the process of vesicle fusion using the following terms.  Please underline the terms in the paragraph. Rab proteins v-SNARE t-SNARE Rab-effectors trans-SNARE complex Rab-GEF NSF (AAA ATPase)      

Acetylcholine binds to a GPCR on heart muscle, making the heart beat more slowly. The activated receptor stimulates a G protein, which opens a K+ channel in the plasma membrane. Which of the following would enhance this effect of the acetylcholine?

7.  Convert 8.5 g/cm3  to  kg/m3

9.  Convert 800 mm to meters