35 y/o man with 3 yr history of enlarging nose, coarse facies, muscle weakness, increased hand/foot size. Large fleshy nose and prognathism on exam. High IGF-1 in serum. MRI shows pituitary adenoma. Morphologic analysis of the tumor shows a densely granulated somatotroph adenoma. Further studies show that the G alpha-s subunit of the tumor G proteins lack GTPase activity. The tumor cells most likely have an increased activity of which enzyme?

Question

Shane Stanley

Biology

9 February, 03:56

35 y/o man with 3 yr history of enlarging nose, coarse facies, muscle weakness, increased hand/foot size. Large fleshy nose and prognathism on exam. High IGF-1 in serum. MRI shows pituitary adenoma. Morphologic analysis of the tumor shows a densely granulated somatotroph adenoma. Further studies show that the G alpha-s subunit of the tumor G proteins lack GTPase activity. The tumor cells most likely have an increased activity of which enzyme?

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Answers (1)

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Wade Mora · Answer 1

Adenylyl Cyclase

Explanation:

The tumor cells most likely have an increased activity of enzyme Adenylyl cyclase.

Since the G alpha-S subunit lacks the GTPase activity, the GTP will not be hydrolized to GDP. As a result the activity of G protein or G subunit will not be inhibited. Thus their respective enzymes will remain active.

An increased activity of Gs Subunit will thus lead to increased activity of enzyme adenylyl cyclase.