Cell Signaling Flashcards
How does the endocrine work for cell signaling?
Uses hormones. Hormones are manufactured and secreted by cells in the endocrine glands, travel in the bloodstream, and then bind to receptors on the cell surface or inside the cell
Where do water-soluble hormones bind?
On the cell surface
Where do lipid-soluble hormones bind?
Inside the cell
What is a common example of a second messenger system?
G-proteins
Describe the basic flow of a second messenger system
Signaling molecules or hormones bind to membrane receptors on the external surface of the plasma membrane. This sets of a cascade of events that increases the size of the signal and after multiple steps stimulates the target cellular response
Steps in G-protein response?
1) Hormone or signal molecule binds to G-cprotein coupled receptor (GCPR), initiating a conformational change that activates a cytosolic domain in that protein)
2) G-proteins are made up of an alpha, beta, and gamma subunit. When GDP is bound protein is off. When GTP is bound protein is on. The signal receptor acts as catalyst for replacement of GDP by GTP, which activates the alpha subunit.
3) Alpha subunit of the G protein separates and acts as agonist for another enzyme such as adenyl cyclist (catalyzes conversion of ATP to cAMP and 2Pi)
4) cAMP is agonist for protein kinase A which phosphorylates proteins (enzymes)
Intracellular Receptors cell final by?
Intracellular receptors are lipid-soluble hormones such as steroids that do not require a plasma membrane surface receptor because they dissolve through the membrane and bind directly to targets in the cytosol. Once their target is activated, it acts inside the nucleus on the promoter region of a gene to regulate transcription up or down
What is a paracrine response? Give an example.
Signal molecules secreted by one cell bind to receptors on other cells in the LOCAL area.
ie. Neurotransmitters acting in synaptic gap
What is an autocrine response?
Signal molecules secreted by a cell bind to receptors on the SAME cell
What is an intracrine response?
Signal molecules (usually steroids) bind to receptors inside the same cell that produced them, without ever being secreted outside of the cell
What is a juxtacrine response?
Signaling requires direct contact between two cells
How does the nervous system perform cell signaling?
Communication between cells done via electrical potentials carried on neurons. Pre-synaptic to post-synaptic. Generally initiates a signaling cascade.
