drosopterin

Drosopterin is a red-orange pigment that belongs to the pterin family and occurs in the compound eyes of Drosophila and several other insects. It is one of the principal eye pigments in Drosophila species and contributes to eye color in combination with other pigments such as ommochromes.

Biosynthesis and chemistry: Drosopterin is derived from the pterin biosynthetic pathway starting with guanosine triphosphate (GTP). In insects, the pathway produces dihydropterin derivatives that are eventually converted into drosopterin. The specific enzymes and steps can vary among species, but drosopterin is generally produced in retina tissue and stored in pigment granules within the eye.

Role in biology: Eye color in Drosophila results from the interaction of multiple pigments. Drosopterin, together with ommochrome pigments like xanthommatin, helps determine red versus brown coloration patterns in the eye. Mutations that affect pterin metabolism or pigment transport can alter drosopterin levels and, consequently, eye color.

Occurrence and significance: Drosopterin has been studied mainly in Drosophila melanogaster and related dipteran species. Beyond its role as a pigment, pterins can participate in various biochemical processes in other contexts, though drosopterin itself is principally described as a pigment component of the insect eye.

Research and applications: Because eye color is a classic genetic trait, drosopterin serves as a marker in studies of pigment pathways, genetics, and metabolism. Its levels help illuminate interactions between biosynthetic enzymes and pigment transport mechanisms that shape the visible coloration of the eye.