Interference 102,728
This interference concerns a DNA construct which comprises a sequence
encoding an "-factor leader sequence derived from the yeast genus, Saccharomyces,
followed by a codon which encodes a lysine (lys) or an arginine (arg) residue and a
second codon which encodes an arginine.7 The second arg codon is directly linked to a
DNA sequence which encodes a polypeptide which is foreign to Saccharomyces
(designated as Gene* in Count 1). Thus, the DNA construct of the count lacks the
sequence which encodes the “glu-ala” portion of the " factor spacer sequence. The
formula of the count is directed to a DNA construct which comprises a nucleotide
sequence which encodes:
Leader - lys-arg- Gene*
or
Leader - arg-arg- Gene*
The DNA construct is said to be useful for the expression and secretion of heterologous
(i.e., foreign) proteins in yeast. This is because the aforementioned combination of
amino acids; i.e., lys/arg and arg/arg, are recognized and cleaved by the yeast enzyme,
KEX2. Such cleavage results in the release of a mature, biologically active protein
7 For purposes of background, we point out that DNA is a polymer composed of
four (4) different mononucleotides; deoxyadenylate (A), deoxyguanylate (G),
deoxycytidylate (C) and thymidylate (T). Amino acids are encoded by groups of
nucleotides known as codons which are composed of three adjacent nucleotides.
Thus, if a group of three nucleotides encodes a single amino acid, then theoretically
(ignoring stop codons) 64 or (43) different amino acids could be formed. However, there
are only twenty (20) different naturally-occurring amino acids. Therefore, most amino
acids are coded for by more than one codon. This phenomenon is known as codon
degeneracy or redundancy.
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Last modified: November 3, 2007