Component of the acid-resistance (AR) system allowing enteric pathogens to survive the acidic environment in the stomach (Probable). ADC can be found in two forms: biodegradative (this enzyme) and biosynthetic (speA). The biodegradative form plays a role in regulating pH by consuming proteins. Converts arginine imported by AdiC to agmatine which is then exported by AdiC (Probable). H(+) + L-arginine = agmatine + CO2 Binds one cofactor per subunit. Homodimers are probably inactive, their assembly into a homodecamer at low pH requires neutralization of negatively charged residues. This uses cytoplasmic protons, contributing pH regulation and stabilizes the homodecamer. Homodecamer. The basic unit is a homodimer, organized into a ring of giving a pentamer of five homodimers. Under conditions of acidic pH, anaerobiosis and rich medium. Forms an operon with downstream adiY but not (further) downstream adiC. Loss of formation of agmatine, loss of arginine-dependent acid resistance. Belongs to the Orn/Lys/Arg decarboxylase class-I family. Extended N-terminus. Extended N-terminus.