Question

Indicate true (T) and false (F) statements below regarding cellular signaling mediated by nitric oxide (NO). Your answer would be a four-letter string composed of letters T and F only, e.g. TTTF.

1. Once produced, NO can diffuse to neighboring cells.
2. NO has known roles in cGMP-independent as well as cGMP-dependent signaling.
3. NO normally decreases cGMP concentration by activating cGMP phosphodiesterase.

Answer 1

NO can diffuse across the plasma membrane and affects both cGMP-dependent and independent signaling pathways. However, it increases cGMP levels in cells by activating guanylate cyclase, not by activating cGMP phosphodiesterase.

Step-by-step explanation:

The provided statements regarding cellular signaling mediated by nitric oxide (NO) can be addressed as follows:

True - NO can indeed diffuse to neighboring cells, as it is able to pass directly across the plasma membrane due to its gaseous state.

True - NO is involved in both cGMP-dependent and cGMP-independent signaling pathways, participating in various cellular functions.

False - Contrary to the statement, NO actually leads to an increase in cGMP concentration in the target cells by activating guanylate cyclase, which converts GTP to cGMP.

Therefore, the correct four-letter string composed of letters T and F only for the provided statements is TTFF.