The construction, identification and characterisation of plasmids containing human α-lactalbumin cDNA sequences

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Abstract
We describe the cloning of double-stranded cDNA synthesized from lactating human mammary gland total poly(A)-containing RNA, into the EcoRI site of the plasmid pAT153. Nine recombinants were shown to contain α-lactalbumin cDNA sequences as determined by positive hybridisation translation of complementary RNA. Restriction enzyme maps were determined for six of these. Alignment of the restriction map with the known amino acid sequence of human α-lactalbumin provided evidence that two plasmids, designated phO-53 and phB-35, contained the complete coding sequence of the primary translation product (pre-α-lactalbumin). Hybridisation studies using purified human, monkey and guinea-pig α-lactalbumin cDNA demonstrated that greater nucleotide sequence divergence has occurred within the rodents than the primates, and that rodent α-lactalbumin mRNAs retain regions of homology with primate α-lactalbumin mRNAs.