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1. In trimeric G proteins, GTP binds to: the alpha subunit. the beta subunit. th

ID: 173622 • Letter: 1

Question

1. In trimeric G proteins, GTP binds to:

the alpha subunit.

the beta subunit.

the gamma subunit.

the activated trimer.

2. Phosphatidylinositol 4,5-bisphosphate (PIP2) is cleaved by phospholipase C into:

1,2-diacylglycerol (DAG).

phosphatidylinositol (PI).

inositol 1,4,5-trisphosphate (IP3).

1,2-diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3)

3. 1,2-diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3) are cleaved from phosphatidylinositol 4,5-bisphosphate (PIP2) by the enzyme:

adenylyl cyclase.

phosphodiesterase.

phospholipase C.

protein kinase C.

a.

the alpha subunit.

b.

the beta subunit.

c.

the gamma subunit.

d.

the activated trimer.

Explanation / Answer

In General protein coupled receptor the GTP binds to alpha subunit of the trimeric G protein. By the action of phospho lipase C , the given compound cleaved to diacylglecerol and inositol triphosphate. The enzyme is phospholipase C.