Storage and secretion of Ag-Aper14, a novel peritrophic matrix protein, and Ag-Muc1 from the mosquito Anopheles gambiae

The gene Ag-Aper14 encodes a novel peritrophic matrix (or peritrophic membrane; PM) protein in the mosquito Anopheles gambiae. The Ag-Aper14 protein is merely 89 amino acids long and has a single putative chitin-binding domain. Prior to blood feeding, the Ag-Aper14 protein is stored in secretory vesicles next to the epithelial cell lumenal surface. Immunoelectron microscopy has revealed that Ag-Aper14 co-localizes to the same secretory vesicles as another PM protein, Ag-Aper1, indicating a common mode of regulated secretion. Conversely, Ag-Muc1, an epithelial cell-surface protein, does not co-localize to these secretory vesicles and is detected only on the cell surface. After blood feeding, Ag-Aper14 is secreted and incorporated into the PM that surrounds the ingested blood.