Catalyzes the decarboxylation of L-aspartate, 3-sulfino-L-alanine (cysteine sulfinic acid), and L-cysteate to beta-alanine, hypotaurine and taurine, respectively. The preferred substrate is 3-sulfino-L-alanine. Does not exhibit any decarboxylation activity toward glutamate. H(+) + L-aspartate = beta-alanine + CO2 3-sulfino-L-alanine + H(+) = CO2 + hypotaurine H(+) + L-cysteate = CO2 + taurine Activated by Mn(2+). Inhibited by bis-carboxymethyl-trithiocarbonate, ethylxanthogenacetic acid and 2,5-disulfoaniline. Not affected by Li(+) within 0.05-40 mM concentration range. kcat is 6.6 sec(-1) with 3-sulfino-L-alanine (cysteine sulfinic acid) as substrate. kcat is 0.14 sec(-1) with L-aspartate as substrate. Organosulfur biosynthesis; taurine biosynthesis; hypotaurine from L-cysteine: step 2/2. Homodimer. Expressed in kidney and liver not detected in lymphoid tissues and lung. Expressed in kidney, liver and brain. 7 and 4 times higher expression in kidney and liver than in brain, respectively. Low level of detection in skeletal muscle. Expressed in brain, olfactory bulb, liver, skeletal muscle and kidney with the highest expression in liver and lowest in skeletal muscle (at protein level) (PubMed:26327310). Expression in the brain decreases with age as detected from 17 dpc to 12 months. Belongs to the group II decarboxylase family.