Together with MRPL18, acts as a mitochondrial import factor for the cytosolic 5S rRNA. Only the nascent unfolded cytoplasmic form is able to bind to the 5S rRNA (By similarity). Involved in the formation of iron-sulfur complexes, cyanide detoxification or modification of sulfur-containing enzymes. Other thiol compounds, besides cyanide, can act as sulfur ion acceptors. Also has weak mercaptopyruvate sulfurtransferase (MST) activity. hydrogen cyanide + thiosulfate = 2 H(+) + sulfite + thiocyanate Monomer. Expressed in numerous tissues. Contains two rhodanese domains with different primary structures but with near identical secondary structure conformations suggesting a common evolutionary origin. Only the C-terminal rhodanese domain contains the catalytic cysteine residue (By similarity).