国外大学细胞生物学课件 英文课件17.ppt

D103 - Cell Biology - lecture 17 ? 2011 Grant MacGregor & Christine S ü tterlin – All rights reserved Page 1 Lecture 17 – Signaling IV - Second messengers mended Reading: MBOC 5e, pages 904 - 921 Release of Ca 2+ in starfish oocytes following fertilization Production of cAMP in response to serotonin signaling in a neuron D103 - Cell Biology - lecture 17 ? 2011 Grant MacGregor & Christine S ü tterlin – All rights reserved Page 2 ? The first "messenger" is the ligand that binds to a receptor ( although the ligand is never referred to as the "first messenger"). ? Examples of ligands include serotonin (binding to a GPCR), growth factor (binding to a growth factor cell surface tyrosine kinase receptor). ? The term "second messenger"refers to signaling molecules that continue to transmit the initial signaling response inside the cell. (. above, the second messengers are Ca 2+ , IP 3 , DAG ). ? Not all components of a signaling pathway inside the cell are referred to as " second messengers ” ( . PKC is not a second messenger). This term is usually used to refer to small molecules that can diffuse rapidly and whose concentration changes rapidly following receipt of a signal . What is a "second messenger" ? D103 - Cell Biology - lecture 17 ? 2011 Grant MacGregor & Christine S ü tterlin – All rights reserved Page 3 ? Second messengers are small molecules that carry signals inside cells . ? Second messenger molecules are chemically diverse - . – anic ion (Ca 2+)– cyclic nucleotides (cyclic adenosine monophosphate (cAMP), and cGMP ) – lipids ( diacylglycerol (. DAG)) – gas (nitric oxide (NO)) ? Some molecules are hydrophilic (. cAMP, Ca 2+ ) while others are hydrophobic (DAG). ? Different second messengers function in discrete sub-partments . Ca 2+ in cytosol or diacylglycerol ( DAG ) in lipid bilayer . ? Rate of diffusion of second messenger varies - . Ca 2+ - low (!);