Changing which components of GFP can affect its properties like color or brightness?

The properties of Green Fluorescent Protein (GFP), including its color and brightness, can indeed be altered by changing specific key amino acids within its structure. These amino acids are critical because they directly influence the chromophore formation, which is responsible for GFP's fluorescence. For example, mutations in certain amino acids can modify the way the chromophore is formed or its environment, thus affecting the wavelength of light emitted (color) and the intensity of fluorescence (brightness).

The overall stability, folding, and functionality of the GFP molecule are also closely tied to specific amino acid residues. By substituting, deleting, or adding particular amino acids, you can enhance or diminish the properties of GFP, creating variants that fluoresce in different colors or demonstrate different brightness levels. This is why modifying key amino acids is a common technique in protein engineering for creating GFP variants with desired optical properties.