(12 Points) Molecular cell signaling pathways involve multiple biological molecu
ID: 93090 • Letter: #
Question
(12 Points) Molecular cell signaling pathways involve multiple biological molecules that work together to produce a result of a cellular response. Several of these molecules are listed below (a-f). For each, (1) describe the molecule’s general role in any signaling pathway, then (2) give a specific example of each molecule in a pathway that we have studied. What is the specific result of the activity of this molecule in your cellular pathway?
a. Ligand Receptor b. Kinase c. Ubiquitin Ligase d. Caspase e. Cyclin f. Transcription Factor
Explanation / Answer
1) Ligand receptor , is the extrinsic protein which is present on the cell membrane used to bind the molecules and changes its confirmation upon binding , these are trans membrane proteins embedded in the membrane upon binding of Ligands undergoes phosphorylation and cascade mechanism of cell functioning.
Eg: G protein coupled receptor , Guanidine phosphate ligand receptor are seven pass transmembrane receotor, when the Ligand like hormone, binded to this it undergoes conformational changes results in cell proliferation and differentiation.
2) kinase are the enzymes which used to transfer the phosphate molecule for phosphorylation induced activation of the Ligand receptor, it used for the transfer of pi from ATP to the substrate, Eg: hexokinase which transfer phosphate molecule from ATP to Glucose to form Glucose 6 phosphate.
3)Ubiquitin ligase :- these are cellular proteins which are very useful in molecular signaling pathways, these are enormous classified into various forms based on the function, Eg: CHIP a co chaperone protein involved in the protein folding, several heat shock proteins HSPs also interacted with it, cyclins in cell cycle and regulations, ubiquitination post translation modifications, cdc20 anaphase promoting factor etc are example for ubiquitination ligase examples.
D) Caspases :- cysteine aspartic serine proteases which are cytoplasmic and nuclear proteins which involves in the cell programming, these are normally zymogens, activated by the phosphorylation. When cell tends to undergo apoptosis either intrinsic or extrinsic pathway which activates caspases8 proteins.
Cyclins:- these are proteins which are cell cycle regulators used for the controlling of cell cycle , when these are phophorylated there are undergoes activation and cell division occurs, if it is inactivated cell cycle arrest at check points . Eg: CdcK Cyclins.
F) transcription factors or TF are the protein which regulates eukaryotic transcription, these are TFIID,. E,A,B,C,F which sequential bindings of these regulates cellular transcription process.
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