These two isoforms show no difference in their biological activity .
Isoforms differ only at the N - terminus where the long isoform ( AdK - long ) contains extra 21 amino acids that replace the first 4 amino acids of the short isoform ( AdK - short ) .
These two isoforms show no difference in their biological activity and they differ only at the N - terminus where the long isoform ( AdK - long ) contains extra 21 amino acids that replace the first 4 amino acids of the short isoform ( AdK - short ) .