Figure 5.

The entire cytoplasmic region of syntaxin 18 is responsible for inhibition of Fc receptor–mediated phagocytosis in 293T/RIIA-FLAG cells. (A) Schematic representation of syntaxin 18 and the mRFP-syntaxin 18 constructs. mRFP was fused to the N-terminus of all constructs. The SNARE-motif and TMD represent a coiled-coil and a transmembrane domain, respectively. (B) 293T/RIIA-FLAG cells were transfected with the mRFP-tagged syntaxin 18 variants or the N-terminally mRFP-tagged VAMP3 ΔTMD, which lacks the transmembrane domain. After 12 h, the cells were incubated with IgG-opsonized latex beads for 40 min and then the incompletely ingested beads were stained with Alexa 488–labeled anti-rabbit IgG antibodies before permeabilization. The association index (left panel) and the phagocytosis index (right panel) were calculated from 50 transfected cells per condition. Data presented are the mean ± SE of four independent experiments (*p < 0.01, as compared with mRFP).