Use sed (or other command line) to replace a set of characters with a different set

Question

I need to invert a DNA text string by changing all the A's to T's, T's to A's, C->G, and G->C.

Can I elegantly handle this in sed (or other command line) without a whole chain of sed global replace commands?

Answer 1

this is how you do it with sed

$ echo "test ATCG GATC test" | sed 'y/ATCG/TAGC/'
test TAGC CTAG test

Answer 2

use tr.
cat file | tr ATCG TAGC