Genetic and physical analysis of the chicken tk gene

Several aspects of the structure of the chicken thymidine kinase gene (tk) have been resolved as a result of genetic experiments and nucleotide sequencing. Deletion mapping established the locations of two functional boundaries in a region thought to correspond to the 5' terminus of the gene. One such boundary coincides with a transcriptional promoter, and the other coincides with the translation start codon of the chicken tk polypeptide. Similar deletion mapping assays identified a functional boundary at the 3' terminus of the gene. DNA sequence analysis confirms the prediction that this 3' region encodes the carboxyl terminus of the tk polypeptide. A recombinant cDNA clone complementary to genomic tk sequences was isolated. A comparison between genomic and cDNA sequences reveals the locations of six intervening sequences and allows prediction of the complete amino acid sequence of the chicken tk polypeptide.