BIOL 300 Lecture Notes - Guanylyl Cyclase, Signal Transduction, Cortisol

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 300
• Professor: Siegfried Hekimi

Document Summary

So far, we have discussed membrane bound cell- surface receptors: there is also a tiny class of intracellular receptors, whose ligands are able to freely diffuse into the cell. As soon as they bind to the receptor, they activate it; these active receptors are transcription factors which can activate gene expression. Hydrophobic hormones have a very slow turnover time (very stable), so you can"t mediate in fast physiological responses: they mediate long responses, involving gene expression. Two important words: agonist; any compound which acts like the hormone (bind and activates the receptor, antagonist; any compound which binds the compound and does not activate it (prevents action), and blocks access to the real hormone. Pharmaceutical companies often screen for various agonists and antagonists in order to create drugs. Nitric oxide, a gas, uses yet another intracellular receptor; it diffuses into the cell and binds guanylyl cycle. Smc relaxation allowing blood flow to produce an erection.