Endocytosis and intracellular dissociation rates of human insulin-insulin receptor complexes by quantum dots in living cells

Bioconjug Chem. 2013 Mar 20;24(3):431-42. doi: 10.1021/bc300526d. Epub 2013 Feb 14.

Abstract

Insulin signaling is involved in glucose metabolism, cellular growth, and differentiation. Its function is altered in diabetes and many cancer types. Insulin binding to insulin receptor (IR) triggers diverse signaling pathways. However, signal transduction by IR is not mediated exclusively at the cell surface. Activated ligand-receptor complexes are internalized into endosomes from which the IR recruits adapters acting on substrates that are distinct from those accessible at the membrane. We report the biotinylation of human-recombinant insulin (rhIns) specifically at the position 29 of the B chain. We combined visible fluorescent proteins fused to IR and biotinylated rhIns conjugated with streptavidin-quantum dots to perform extended, quantitative experiments in real time. Modified rhIns bound to the IR and conjugated with the quantum dots was internalized with a rate constant (k) of 0.009 min(-1). Dissociation of insulin-IR complex in endocytosed vesicles occurred with k = 0.006 min(-1).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, CD / chemistry
  • Antigens, CD / genetics
  • Antigens, CD / metabolism*
  • COS Cells
  • Chlorocebus aethiops
  • Endocytosis / physiology*
  • HEK293 Cells
  • HeLa Cells
  • Hep G2 Cells
  • Humans
  • Intracellular Fluid / chemistry
  • Intracellular Fluid / metabolism*
  • Molecular Sequence Data
  • Quantum Dots*
  • Receptor, Insulin / chemistry
  • Receptor, Insulin / genetics
  • Receptor, Insulin / metabolism*

Substances

  • Antigens, CD
  • INSR protein, human
  • Receptor, Insulin