Lymphotactin (Ltn), involved in white blood cell activation, represents a new class of proteins known as âmetamorphic proteinsâ. Ltn exists in two very different structures that are in thermal equilibrium: conformation Ltn40 exists as a dimer made up of all beta-strands and binds glycosaminoglycans (GAGs), and conformation Ltn10 exists as a monomer, contains an beta-helix and activates G-protein coupled receptors (GPCRs). Both conformations are needed for the biological function of Ltn. (11 points) a. Taking into account that the dimer in Ltn40 is stabilized by an intermolecular salt bridge (Lys25- Glu31), why might the Ltn10 conformation be favored under high salt concentrations? (6) b. Sketch a two-dimensional conformational energy landscape diagram for Ltn in its ligand-free state (i.e. protein is not bound to GAG, GPCR, etc.). (5)
Lymphotactin (Ltn), involved in white blood cell activation, represents a new class of proteins known as âmetamorphic proteinsâ. Ltn exists in two very different structures that are in thermal equilibrium: conformation Ltn40 exists as a dimer made up of all beta-strands and binds glycosaminoglycans (GAGs), and conformation Ltn10 exists as a monomer, contains an beta-helix and activates G-protein coupled receptors (GPCRs). Both conformations are needed for the biological function of Ltn. (11 points) a. Taking into account that the dimer in Ltn40 is stabilized by an intermolecular salt bridge (Lys25- Glu31), why might the Ltn10 conformation be favored under high salt concentrations? (6) b. Sketch a two-dimensional conformational energy landscape diagram for Ltn in its ligand-free state (i.e. protein is not bound to GAG, GPCR, etc.). (5)
