Insulin stimulates glucose uptake in adipocytes primarily by:

• A Increasing cAMP, which activates PKA to phosphorylate GLUT4 vesicles
• B Directly binding GLUT4 to increase its intrinsic transport activity
• C Activating PI3K→PDK1→Akt pathway causing GLUT4 vesicle translocation to plasma membrane ✓
• D Activating adenylyl cyclase via Gs protein

Explanation

Insulin receptor (tyrosine kinase) autophosphorylates, recruits IRS-1, activates PI3K, generating PIP3, which recruits PDK1 and Akt; Akt phosphorylates AS160, releasing GLUT4-containing vesicles to fuse with the plasma membrane. cAMP is used by glucagon, not insulin. GLUT4 intrinsic activity is not the regulated step. Insulin receptor is not a GPCR.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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