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 Organosulfur biosynthesis; taurine biosynthesis; hypotaurine from L-cysteine: step 2/2. Homodimer. Expressed in brain, liver and kidney. Belongs to the group II decarboxylase family.