DNA sequence coding for an antifreeze protein precursor from winter flounder.

A cDNA made to antifreeze protein mRNA of the winter flounder was cloned in the plasmid pBR322 and its sequence was determined by the method of Maxam and Gilbert. Its sequence codes for a precursor protein that is 82 amino acids in length. This precursor has both a signal polypeptide and a prosequence before the mature protein of 38 amino acid residues. The mature protein matches in composition one of the alanine-rich serum antifreeze proteins that was purified by ion-exchange and reverse-phase chromatography. The composition of the pro- sequence is similar to that of the native protein except that it contains five prolines. The mature protein, but not the pro- sequence, contains three of the 11-residue repeats previously observed [Lin, Y. & Gross, J. K. (1981) Proc. Natl. Acad. Sci. USA 78, 2825-2829] in two other antifreeze protein components.