Compare two ways that the binding of a signal molecule to a receptor protein causes a change in activity the receiving cell?

Answer 1

1. Insulin binding to insulin receptor tyrosine kinase on hepatocyte: increased glucose uptake, increased glycogen and fatty acid production and decreased catabolism in general (decreased gluconeogenesis, lipolysis, and proteolysis). Insulin binding causes receptor dimerization and self-phosphorylation. Phosphorylated receptor recruits scaffold proteins and downstream target proteins and phosphorylate them. Phosphorylated target proteins serve as kinases and activate or deactivate other proteins by phosphorylation, effecting appropriate effects. 2. Erythropoietin binding to EPO cytokine receptor on Common Myeloid Progenitor cell: eventual differentiation into erythrocyte. Cytokine receptor induces the Jak/STAT pathway resulting in altered gene expression by transcription factors, drastically changing the function and morphology of the cell.