4A. (3pts) One of the following statements is generally accurate, and the other

Question

4A. (3pts) One of the following statements is generally accurate, and the other one is not. Please put an "A" next to the accurate statement and provide a supporting example. Please put an "" next to the inaccurate statement and provide a counter-example. GEF's activate signaling proteins, while GAP's inactivate them Supporting or counter-example: Kinases activate signaling proteins, while phosphatases inactivate them. Supporting or counter-example: B. (3pts) Do you AGREE or DISAGREE with the following? Please provide your reasoning. The changes that kinases and phosphatases make to proteins are both energetically favorable. or DISAGREE

Explanation / Answer

(A) "A" GEF's activate signalling proteins while GAP's inactivate them.

Because its an accurate statement.

Example is signalling pathway of Ras. The Ras-GDP bound state is exchanged for GTP by GEF (Guanine nucleotide exchange factor) leading to activation and commencement of the signalling pathway. While the biding of GDP inactivates it.

"I" Kinases activate signalling proteins while phosphatases inactivate them.

Because the statement is inaccurate to some extent.

For example, Lck is a Src family tyrosine kinase. Here, the phosphatase acts as a positive regulator of signalling pathway where the phophorylated form of Lck is inactive and release of the phosphate group will make it active.

(B) AGREE, because the changes that kinases and phosphatases make to proteins are energetically favourable. The reversible activation of these enzyme allows the cell to regulate the signalling pathways effectively.

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