The invention concerns polynucleotide sequences of formula: B-GTTACCAACTACCTAGACTGGATTCGTGACAAC-D-E-GTCGACAAGCTT, wherein B denotes a polynucleotide sequence encoding human tissue plasminogen activator or its variants, insertions or deletions from one or more codons, D denotes a nucleotide sequence which includes a recognition sequence for a restriction enzyme, and E denotes a translation stop codon. These vectors can be used to insert nucleotide sequences encoding specific amino acids according to the genetic code at or near the C terminus of the plasminogen activator.
