The Drosophila reticulon, Rtnl-1, has multiple differentially expressed isoforms that are associated with a sub-compartment of the endoplasmic reticulum

The reticulons are a recently discovered family of proteins that have a predominant localisation to the membrane of the endoplasmic reticulum. The precise function of the reticulons is unclear despite their presence in a wide variety of eukaryotic organisms. Here we describe the characterisation of the Drosophila reticulon, reticulon-like 1 (Rtnl1), which is the only functional reticulon in Drosophila. The Rtnl1 locus produces seven predicted mRNA transcripts encoding five different protein isoforms. The different transcripts have tissue-specific expression patterns remarkably similar to their mammalian counterparts. Rtnl1 protein is associated with organelles of the secretory pathway including the endoplasmic reticulum and the Golgi apparatus. Rtnl1 function appears to be non-essential or redundant since loss of function Rtnl1 mutants are viable. However, a significant reduction in life expectancy was seen in Rtnl1 mutant flies. This may point towards a possible protective role for reticulons against conditions of environmental stress.