Mater encodes a maternal protein in mice with a leucine-rich repeat domainhomologous to porcine ribonuclease inhibitor

MATER (Maternal Antigen That Embryos Require) is an ooplasm-specific protei n first identified as an antigen (OP1) associated with ovarian autoimmunity in mice. Its primary structure has been deduced from full-length cDNA that encodes a 125-kDa protein required for progression of the mouse embryo bey ond two cells. Expression of the gene encoding MATER is restricted to the o ocyte, which makes it one of a growing, but still limited, number of matern al-effect genes in mammals. To further investigate the function of MATER du ring oogenesis and early development, we have characterized the gene and re sultant protein. Mater is a single-copy gene in the genome of 129/Sv mice a nd is located at the proximal end of Chromosome (Chr) 7. The gene, spanning approximately 32 kbp, contains 15 exons ranging in size from 48 to 1576 bp , which together encode the 1111 amino acid MATER protein. The first five e xons encode 26-27 amino acid hydrophilic repeats, and exons 8-14 encode 14 leucine-rich repeats. The three-dimensional structure of the latter domain can be closely modeled on the previously determined X-ray crystallographic coordinates of porcine ribonuclease inhibitor. These characterizations of t he gene and protein provide the basis for genetic investigations of MATER f unction in early mammalian development.