PNB 2274 Lecture Notes - Lecture 24: Circadian Rhythm, Adrenal Medulla, Beta Cell
12 Apr 2018
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Depending on if hormones are water soluble or not, different functions and mechanisms. Steroid and thyroid hormones, lipid solubility allows passage thru membrane, so have intracellular receptors and can activate gene transcription. Peptide and amine hormones can only reach the cell membrane, has receptors like antennas, will cause a downstream effect with a second messenger system. A g-protein related pathway. g protein coupled receptors have 3 subunits: alpha, beta and gamma. The alpha subunit will cause signal, beta and gamma will do its own thing. Unknown function of beta and gamma, they have signaling pathways too. It can also attach to the cre protein that goes to nucleus to initiate transcription. Usually just acting as 2nd messenger, turn on other enzymes to start chain rxn. Can also activate protein kinase a, which will cause phosphorylation, which is to add a po4 to a molecule to activate a protein, may dictate the shape, activity, stability, conformation, binding partners, or localization.
