Antifreeze protein genes of the winter flounder.

A genomic library of the winter flounder in lambda phage Charon 4 was screened with antifreeze protein cDNA. Nine genomic clones were isolated from three haploid genome equivalents of phage and were grouped into three classes on the basis of restriction mapping and heteroduplex analysis. The three chromosomal regions are non-overlapping and each contain two antifreeze protein genes spaced from 3 to 7 kilobase pairs apart. Genomic Southern blots indicate that these six non-allelic genes represent only 10-20% of the complement of this large multigene family. One gene has been identified by sequencing as a variant of the gene encoding the most abundant antifreeze protein. This gene is 1.0 kilobase pair long and contains an intervening sequence of 0.6 kilobase pairs between the coding region for the bulk of the signal sequence and that coding for the proprotein.