Characterization of two novel casein transcripts in rabbit mammary gland.

Two clones were isolated from a cDNA library corresponding to mRNAs which accumulate in mid-lactating (14 day) rabbit mammary gland and characterized by DNA sequencing. The two clones sequenced corresponded to two novel casein transcripts (pBRM5 and pBRM42). Relative mRNA abundances for the two clones were assessed by dot-blot analysis. Phylogenetic analysis and comparison of both pBRM5 and pBRM42 with other members of the casein family revealed that the rabbit may be unique among mammals in expressing two alpha s2-casein genes. The presence of two alpha s2-casein genes in the rabbit may be the result of a relatively recent intergenic duplication event.