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Biochemistry & Molecular Biophysics

Jefferson Knight

​Dr. Jefferson Knight’s research explores mechanisms of molecular interaction that underlie the biological process of insulin secretion.

Living cells are not just bags of molecules in solution!  Rather, they have many compartments (organelles) that provide structure and organization to the biochemical reactions that take place inside.  The surface of each of these compartments (and also the surface of the cell itself) is a membrane – a flexible, fluid sheet containing lipid and protein molecules that provide structure and perform important functions.  For example, membrane surfaces provide scaffolds for many signaling processes, such as the glucose-stimulated secretion of the hormone insulin.

Research in the Knight lab aims to understand interactions of lipid membranes with signaling proteins important to pancreatic beta cells – the cells responsible for secreting insulin in humans.  In particular, our studies focus on proteins and protein domains that interact reversibly with membranes in response to intracellular signals. There are dozens of these membrane-targeting proteins involved in signaling pathways specific to beta cells, and for many the precise mechanisms of membrane interaction are not well understood.  A better understanding of these protein-membrane interactions will yield insight not only into the basic mammalian process of insulin secretion, but also into disorders of beta cells such as pancreatic cancer and type II diabetes.

The techniques used in the Knight lab span the disciplines of biology, chemistry, and physics.  These include:

  • molecular cloning
  • protein purification via affinity and gel-filtration chromatography
  • fluorescence spectroscopy-based membrane binding assays
  • single-molecule optical microscopy. 

Individual projects use various combinations of these techniques, and may involve collaboration with other groups on or off campus.

Current Research Projects:

  • Using kinetic and steady-state fluorescence spectroscopy, characterize membrane binding properties of C2 domains from synaptotagmin proteins involved in insulin secretion.

  • Using site-directed mutagenesis and the above techniques, determine the amino acid residues responsible for membrane insertion of a protein domain with interesting properties.

  • Using single-molecule fluorescence microscopy to measure lateral diffusion constants, determine the extent and nature of protein-protein interactions at a membrane surface.

  • Using cell biological and organic/analytical chemistry techniques, measure changes in membrane lipid composition that arise from exposing insulin-secreting cells to diabetes-like conditions.