The whole cell protein extract was applied to a 4–12% SurePAGE™ Bis–Tris gradient gel (Genscript, Piscataway, NJ, USA) with 3-(N-morpholino)propanesulfonic acid (MOPS) as running buffer and electrotransferred onto a nitrocellulose membrane using an iBlot 1 dry blotting system (ThermoFisher, Waltham, MA, USA). After washing 3 times with PBS supplemented with 0.1% v/v Tween 20 (PBS/T), the membrane was incubated with 1 µg/mL anti-PAS antibody in PBS/T for 1 h at RT. The membrane was washed 3 times with PBS/T and incubated with a 1:5000 dilution of a goat anti-mouse IgG (Fc-specific) alkaline phosphatase (AP) conjugate (Merck) for 1 h. After washing twice with PBS/T and twice with PBS, the blot was developed by a chromogenic reaction using BCIP (37.5 µg/mL) and NBT (150 µg/mL) in alkaline phosphatase buffer (100 mM Tris/HCl, pH 8.8, 100 mM NaCl, 5 mM MgCl2).