Chapter 20, Problem 17P

Interpretation Introduction

Interpretation:

Suppose that you had a monoclonal antibody that recognized phosphotyrosine. To explain how that antibody would affect insulin signaling.

Concept Introduction:

The Insulin Receptor autophosphorylates the tyrosine residues. The added phosphate groups form a docking site for phosphorylated IRES-1 which subsequently initiates downstream signal transduction. IRS-1 binds to PI3K which catalyses the conversion of phosphatidylinositol 4,5-bisphosphate into phosphatidylinositol 3,4,5-trisphosphate (PIP3).

PIP3 activates PKB that takes a two pronged action: one it prepares the cell for glucose absorption and two it phosphorylates and inhibits glycogen synthase kinase, which inhibits glycogen synthase.