Saglin is a 50kDa protein in the salivary gland of Anopheles gambiae that was proposed to be an essential receptor for sporozoites of Plasmodium berghei and P.falciparum, allowing the sporozoites to recognize and infect the mosquito salivary gland.Spatial and temporal patterns of Saglin expression reported here, however, suggest that some modifications to this model are needed.Saglin protein was detected by indirect immunofluorescence microscopy only in the medial and proximal-lateral lobes but not in the distal-lateral lobes of the salivary glands of A.gambiae;the pattern of expression was independent of mosquito age or physiological state.These results were confirmed by steady-state Saglin transcript and protein analysis using qRT-PCR and Western-blot analysis, respectively.Moreover, Saglin was localized to the basal surface of the cells of the medial lobes and was undetectable within the cells, the lateral and apical membranes, the cells secretory cavities or in the salivary duct.In the cells of the proximal lateral lobes of the salivary glands, Saglin was distinctly intracellular and was not localized to any of the cell surfaces.Transgenic Anopheles stephensi were produced that expressed A.gambiae Saglin in the distal lateral lobes of the salivary gland.Additional Saglin expression did not enhance infection by P.falciparum sporozoites compared to non-transgenic siblings fed on the same gametocyte-containing blood meal.The absence of Saglin in the distal lateral lobes of the salivary glands, a primary destination for sporozoites, suggests that Saglins role is something other than an essential receptor for Plasmodium.