cDNA cloning and sequencing of a new gene intensely expressed in early differentiation stages of embryonal carcinoma cells and in mid-gestation period of mouse embryogenesis.

By the differential hybridization technique, we isolated a cDNA clone, MK1, whose RNA level increased in early stages of retinoic acid-induced differentiation of embryonal carcinoma cells. The amount of MK1 RNA progressively decreased in the later stages of the differentiation. In mouse embryos, MK1 RNA was abundant in mid-gestation stages (Day 8 to Day 11) and decreased thereafter. The corresponding RNA was 1.0 killobase in size. From the nucleotide sequence, MK1 gene was predicted to code a polypeptide of molecular weight 9,971, which was rich in basic amino acids.