Pmg-1 and Pmg-2 constitute a novel family of KAP genes differentially expressed during skin and mammary gland development

The study identified two novel genes, pmg-1 and pmg-2, which formed a new family of keratin-associated proteins (KAPs) involved in the differentiation of epithelial cells in skin and mammary glands. These intron-less genes were transcribed in opposite directions and shared a promoter region with binding motifs for developmental transcription factors. They were expressed in hair follicles, sebaceous, and eccrine sweat glands, with mammary epithelium expression limited to puberty onset and independent of ovarian hormones. The proteins encoded were small, rich in specific amino acids, and distinct from other KAP families, playing a role in epidermal appendage development and potentially conserved between mice and humans.