Chapter 2: Understanding Structure—Function Relationships in the Aequorea victoria Green Fluorescent Protein

Abstract

Publisher Summary Learning the physiological role of green fluorescent protein (GFP) and its interaction with aequorin could help understand how to create mutants that exhibit efficiency energy transfer and how to effectively control dimerization. The interaction of GFP with aequorin is readily reversible and is stabilized by high protein and salt concentrations—conditions likely to be encountered within the light-emitting organelles of Aequorea victoria. Both GFP and aequorin can dimerize under appropriate conditions, and it is the dimerized forms that are believed to interact. The molecular details of the interaction of aequorin with GFP are unknown, although it has been suggested that a C-terminal hydrophobic patch, deriving from amino acids 206,221, and 223, or a stretch of negative electrostatic potential could be plausible interaction domains. Although the significance of the heterogeneity of both GFP and aequorin has largely been ignored, it is possible that it favors the correct association of GFP with aequorin. At least one site of heterogeneity in the Aequorea-derived GFP nucleotide residues occurs at a position involved in GFP Dimerization. Isoform variation at this position was split between positively and negatively charged amino acids, which would favor the selective association of different isoforms.