Human transferrin: cDNA characterization and chromosomal localization.

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Abstract
Transferrin (Tf) is the major Fe binding protein in vertebrate serum. It shares homologous amino acid sequences with 4 other proteins: lactotransferrin, ovotransferrin, melanoma antigen p97 and HuBlym-1. Antigen p97 and the Tf receptor genes have been mapped on human chromosome 3. The characterization of the Tf gene was initiated by identifying and characterizing its c[complementary]DNA and mapping its chromosomal location. Recombinant plasmids containing human cDNA encoding Tf were isolated by screening an adult human liver library with a mixed oligonucleotide probe. Within the 2.3 kbase pairs of Tf cDNA analyzed, there is a probable leader sequence encoded by 57 nucleotides followed by 2037 nucleotides that encode the homologous amino and carboxyl domains. During evolution, 3 areas of the homologous amino and carboxyl domains were strongly conserved, possibly reflecting functional constraints associated with Fe binding. Chromosomal mapping by in situ hybridization and somatic cell hybrid analysis indicates that the Tf gene is located at q21-25 on human chromosome 3, consistent with linkage of the Tf, Tf receptor, and melanoma p97 loci.