DNA-binding region of zipper proteins was once thought to be a continuous alpha helix and to protrude from the DNA (top left). A comparison of the amino acid seqeunces of 11 proteins (bottom) showed that certain amino acids in the protrusion were conserved from molecule to molecule (yellow highlighting), suggesting that they aid binding and touch the DNA. Moreover, asparagine (green), a potential helix breaker, was found to lie at a fixed point in the DNA-binding region of every protein. It, then, might allow the protruding section to bend and thus contact the DNA continuously (top right).