CPPS 325 FINAL EXAM With Correct Answers

What are the 5 well-known enzyme-linked cell surface receptors? - Answer 1. Receptor Guanylyl Cyclase: produces cGMP 2. RTK: phosphorylate tyrosine residues leading to association of signalling molecules and cascade 3. TK Associated Receptors: associate with proteins having TK activity 4. Receptor Tyrosine Phosphates: Removes phosphate on tyrosine residues 5. Receptor Serine/Threonine Kinases: phosphorylate specific Serine/Threonine residues on IC signalling molecules How are RTK and TK Associated Receptors different? - Answer RTK phosphorylate tyrosine while associated receptors bind/find proteins with TK activity to initiate the cascade of signalling. What is the reciprocal of RTK? - Answer Receptor Tyrosine Phosphatases. They take the phosphate off the tyrosine residues to inactivate signalling cascades. Ex. Transforming GF Beta superfamily of receptors, cell type dependent. What is the major mechanism for receptor signal transduction? - Answer Tyrosine kinase phosphorylation RTK vs. Serine/Threonine Phosphorylation ? - Answer Tyrosine phosphorylation is rare (1%) relative to serine/threonine residue phosphorylation. Tyrosine phosphorylation is the major mechanism of receptor signal transduction. What is the net effect of activated TKs? - Answer Tyrosine phosphorylation on target proteins. What do TK pathways mediate? - Answer Cell growth (growth factors), differentiation, host defense, metabolic regulation, cell survival pathways (survival factors). What are amplifiers of the TK pathways? - Answer PI3-K - PIP3 PLC - DAG and InsP3&Ca2+ What are RTK mediated actions in the cell? - Answer regulation of cell proliferation, differentiation, and cell motility, promotion of cell survival and modulation of cellular metabolism. TKs exist in either the cytosol or as transmembrane receptors, what are the differences in the two types? - Answer Cytosol receptors have an src N-terminal region. Cytosol has no membrane spanning domain.