purpleoid1, a classic Drosophila eye color mutation, is an allele of the t-SNARE-encoding gene SNAP29

The <i>Drosophila</i> mutant eye color trait <i>purpleoid</i> ( <i>pd</i> ) was first observed by Calvin Bridges over a century ago. Although <i>pd</i> mutant strains have been maintained ever since, the <i>pd</i> locus has not been identified. Using complementation tests, genetic rescue, and DNA sequencing, we show that <i>pd ¹</i> is a missense mutation in <i>SNAP29</i> ; this gene encodes a key component of the SNARE complex, which facilitates vesicle docking and fusion at cellular membranes. After describing how <i>pd ¹</i> was mapped, we discuss ways that the mutation could be used in future studies of eye pigmentation, SNARE complex assembly, and vesicle trafficking.