The present invention provides polynucleotides and related polypeptides of the protein ZMNAM isolated from maize endosperm. The invention provides genomic sequence for the ZMNAM gene. ZMNAM is a novel gene and is regulated by gene-specific imprinting. ZMNAM expression is endosperm-specific and expressed throughout the endosperm development, peaking at 25 DAP. Genomic imprinting has been implicated to play a role in endosperm development. Genes regulated by allele-specific imprinting are suspected to be non-essential to seed development. Gene-specific imprinting however, regulates developmentally important genes. The ZMNAM gene, a putative transcriptional factor, may play an important role in endosperm development, which may further affect kernel size, plant vigor during germination and at the early seedling stage.