Expression of a sterol carrier protein-x gene in the Yellow fever mosquito, Aedes aegypti

The sterol carrier protein-x (SCP-x), a peroxisomal thiolase/nonspecific lipid binding protein, was characterized in the yellow fever mosquito, Aedes aegypti. The Aedes aegypti SCP-x (AeSCP-x) has 83% and 75% similarities to Drosophila and mammalian SCP-x, respectively. However, the AeSCP-x gene did not produce multiple transcripts, which is characteristic of the vertebrate SCP-x gene. Levels of AeSCP-x transcription were higher in larvae and pupae. Gut tissue showed the highest level of AeSCP-x mRNA in larvae. In adults, low levels of AeSCP-x transcription were detected in both sexes. Polyclonal antibodies against the sterol carrier protein-2 (SCP-2) domain of AeSCP-x detected two proteins of 62 kDa and 13 kDa. The results indicate that AeSCP-x is proteolytically cleaved after translation to produce a smaller protein that contains only the SCP-2 domain, which is similar to post-translational modification of the vertebrate's SCP-x to produce multiple products.